Publication Search Results

ID: 159607
Type: article
Authors: Vega, Laura D.; Stassun, Keivan G.; Montez, Rodolfo, Jr.; Kamiński, Tomasz; Sabin, Laurence; Schlegel, Eric M.; Vlemmings, Wouter H. T.; Kastner, Joel H.; Ramstedt, Sofia; Boyd, Patricia T.
Abstract: We present an X-ray through submillimeter observations of the classical RV Tauri (RVb-type) variable U Mon, a post-asymptotic giant branch (AGB) binary with a circumbinary disk (CBD). Our SMA observations indicate a CBD diameter of ≲550 au. Our XMM-Newton observations make U Mon the first RV Tauri variable detected in X-rays. The X-ray emission is characteristic of a hot plasma (∼10 MK), with L_X =5 × 10³⁰ erg s^-1, and we consider its possible origin from U Mon, its companion, and/or binary system interactions. Combining DASCH and AAVSO data, we extend the time-series photometric baseline back to the late 1880s and find evidence that U Mon has secular changes that appear to recur on a timescale of ∼60 yr, possibly caused by a feature in the CBD. From literature radial velocities we find that the binary companion is a ∼2 M_⊙ A-type main-sequence star. The orientation of the binary's orbit lies along our line of sight (ω = 95°), such that apastron corresponds to photometric RVb minima, consistent with the post-AGB star becoming obscured by the near side of the CBD. In addition, we find the size of the inner-CBD hole (∼4.5-9 au) to be comparable to the binary separation, implying that one or both stars may interact with the CBD at apastron. The obscuration of the post-AGB star implicates the companion as the likely source of the enhanced Hα observed at RVb minima and of the X-ray emission that may arise from accreted material.

ID: 159608
Type: article
Authors: Jones, Mackenzie L.; Parker, Kieran; Fabbiano, G.; Elvis, Martin; Maksym, W. P.; Paggi, A.; Ma, Jingzhe; Karovska, M.; Siemiginowska, Aneta; Wang, Junfeng
Abstract: We present the spatial analysis of five Compton thick (CT) active galactic nuclei (AGNs), including MKN 573, NGC 1386, NGC 3393, NGC 5643, and NGC 7212, for which high-resolution Chandra observations are available. For each source, we find hard X-ray emission (>3 keV) extending to ∼kiloparsec scales along the ionization cone, and for some sources, in the cross-cone region. This collection represents the first, high-signal sample of CT AGN with extended hard X-ray emission for which we can begin to build a more complete picture of this new population of AGN. We investigate the energy dependence of the extended X-ray emission, including possible dependencies on host galaxy and AGN properties, and find a correlation between the excess emission and obscuration, suggesting a connection between the nuclear obscuring material and the galactic molecular clouds. Furthermore, we find that the soft X-ray emission extends farther than the hard X-rays along the ionization cone, which may be explained by a galactocentric radial dependence on the density of molecular clouds due to the orientation of the ionization cone with respect to the galactic disk. These results are consistent with other CT AGN with observed extended hard X-ray emission (e.g., ESO 428-G014 and the Ma et al. CT AGN sample), further demonstrating the ubiquity of extended hard X-ray emission in CT AGN.

ID: 159609
Type: article
Authors: Miller, Tim B.; van Dokkum, Pieter; Danieli, Shany; Li, Jiaxuan; Abraham, Roberto; Conroy, Charlie; Gilhuly, Colleen; Greco, Johnny P.; Liu, Qing; Lokhorst, Deborah; Merritt, Allison
Abstract: Stellar-mass estimates of massive galaxies are susceptible to systematic errors in their photometry, due to their extended light profiles. In this study, we use data from the Dragonfly Wide Field Survey to accurately measure the total luminosities and colors of nearby massive galaxies. The low surface brightness limits of the survey (μ_g ≍ 31 mag arcsec^-2 on a 1' scale) allow us to implement a method, based on integrating the 1D surface brightness profile, that is minimally dependent on any parameterization. We construct a sample of 1188 massive galaxies with $\mathrm{log}{M}_{* }/{M}_{\odot }> 10.75$ based on the Galaxy Mass and Assembly (GAMA) survey and measure their total luminosities and g - r colors. We then compare our measurements to various established methods applied to imaging from the Sloan Digital Sky Survey (SDSS), focusing on those favored by the GAMA survey. In general, we find that galaxies are brighter in the r band by an average of ∼0.05 mag and bluer in g - r colors by ∼0.06 mag compared to the GAMA measurements. These two differences have opposite effects on the stellar-mass estimates. The total luminosities are larger by 5% but the mass-to-light ratios are lower by ∼10%. The combined effect is that the stellar-mass estimate of massive galaxies decreases by 7%. This, in turn, implies a small change in the number density of massive galaxies: ≤30% at $\mathrm{log}{M}_{* }/{M}_{\odot }\geqslant 11$ .

ID: 159610
Type: article
Authors: Davies, Rebecca L.; Förster Schreiber, N. M.; Genzel, R.; Shimizu, T. T.; Davies, R. I.; Schruba, A.; Tacconi, L. J.; Übler, H.; Wisnioski, E.; Wuyts, S.; Fossati, M.; Herrera-Camus, R.; Lutz, D.; Mendel, J. T.; Naab, T.; Price, S. H.; Renzini, A.; Wilman, D.; Beifiori, A.; Belli, Sirio; Burkert, A.; Chan, J.; Contursi, A.; Fabricius, M.; Lee, M. M.; Saglia, R. P.; Sternberg, A.
Abstract: We investigate what drives the redshift evolution of the typical electron density (n_e) in star-forming galaxies, using a sample of 140 galaxies drawn primarily from KMOS^3D (0.6 (0.6 (0.6 (0.6 _e in the line-emitting material decreases from 187 ${}_{-132}^{+140}$ cm^-3 at z ∼ 2.2 to 32 ${}_{-9}^{+4}$ cm^-3 at z ∼ 0, consistent with previous results. We use the Hα luminosity to estimate the rms n_e averaged over the volumes of star-forming disks at each redshift. The local and volume-averaged n_e evolve at similar rates, hinting that the volume filling factor of the line-emitting gas may be approximately constant across 0 ≲ z ≲ 2.6. The KMOS^3D and SAMI galaxies follow a roughly monotonic trend between n_e and star formation rate, but the KMOS^3D galaxies have systematically higher n_e than the SAMI galaxies at a fixed offset from the star-forming main sequence, suggesting a link between the n_e evolution and the evolving main sequence normalization. We quantitatively test potential drivers of the density evolution and find that n_e(rms) $\simeq {n}_{{{\rm{H}}}_{2}}$ , suggesting that the elevated n_e in high-z H II regions could plausibly be the direct result of higher densities in the parent molecular clouds. There is also tentative evidence that n_e could be influenced by the balance between stellar feedback, which drives the expansion of H II regions, and the ambient pressure, which resists their expansion.

ID: 159611
Type: article
Authors: Pesce, Dominic W.; Seth, Anil C.; Greene, Jenny E.; Braatz, James A.; Condon, James J.; Kent, Brian R.; Krajnović, Davor
Abstract: We present the results from an observing campaign to confirm the peculiar motion of the supermassive black hole (SMBH) in J0437+2456 first reported in Pesce et al. Deep observations with the Arecibo Observatory have yielded a detection of neutral hydrogen (H I) emission, from which we measure a recession velocity of 4910 km s^-1 for the galaxy as a whole. We have also obtained near-infrared integral field spectroscopic observations of the galactic nucleus with the Gemini North telescope, yielding spatially resolved stellar and gas kinematics with a central velocity at the innermost radii (0"1 ≍ 34 pc) of 4860 km s^-1. Both measurements differ significantly from the ∼4810 km s^-1 H₂O megamaser velocity of the SMBH, supporting the prior indications of a velocity offset between the SMBH and its host galaxy. However, the two measurements also differ significantly from one another, and the galaxy as a whole exhibits a complex velocity structure that implies that the system has recently been dynamically disturbed. These results make it clear that the SMBH is not at rest with respect to the systemic velocity of the galaxy, though the specific nature of the mobile SMBH-i.e., whether it traces an ongoing galaxy merger, a binary black hole system, or a gravitational-wave recoil event-remains unclear.

ID: 159612
Type: article
Authors: Brumback, McKinley C.; Hickox, Ryan C.; Fürst, Felix S.; Pottschmidt, Katja; Tomsick, John A.; Wilms, Jörn; Staubert, Rüdiger; Vrtilek, Saeqa
Abstract: We present a broadband X-ray timing study of the variations in pulse behavior with the superorbital cycle in the low-mass X-ray binary Her X-1. This source shows a 35 day superorbital modulation in X-ray flux that is likely caused by occultation by a warped, precessing accretion disk. Our data set consists of four joint XMM-Newton and NuSTAR observations of Her X-1 which sample a complete superorbital cycle. We focus our analysis on the first and fourth observations, which occur during the bright "main-on" phase, because these observations have strongly detected pulsations. We added an archival XMM-Newton observation during the "short-on" phase of the superorbital cycle because our observations at that phase are lower in signal to noise. We find that the energy-resolved pulse profiles show the same shape at similar superorbital phases, and the profiles are consistent with expectations from a precessing disk. We demonstrate that a simple precessing accretion disk model is sufficient to reproduce the observed pulse profiles. The results of this model suggest that the similarities in the observed pulse profiles are due to reprocessing by a precessing disk that has returned to its original precession phase. We determine that the broadband spectrum is well fit by an absorbed power law with a soft blackbody component and show that the spectral continuum also exhibits a dependence on the superorbital cycle. We also present a brief analysis of the energy-resolved light curves of a pre-eclipse dip, which shows soft X-ray absorption and hard X-ray variability during the dip.

ID: 159613
Type: article
Authors: Sohn, Jubee; Geller, Margaret J.; Hwang, Ho Seong; Fabricant, Daniel G.; Moran, Sean M.; Utsumi, Yousuke
Abstract: HectoMAP is a dense, red-selected redshift survey to a limiting r = 21.3 mag covering 55 deg² in a contiguous 1°5 strip across the northern sky. This region is also covered by the Subaru/Hyper Suprime-Cam (HSC) Subaru Strategic Program photometric survey enabling a range of applications that combine a dense foreground redshift survey with both strong and weak lensing maps. The median redshift of HectoMAP exceeds 0.3 throughout the survey region, and the mean density of the redshift survey is ∼2000 galaxies deg^-2. Here we report a total of 17,313 redshifts in a first data release covering 8.7 deg². We include the derived quantities D_n4000 and stellar mass for nearly all of the objects. Among these galaxies, 8117 constitute a 79% complete red-selected subsample with r ≤ 20.5 mag, and an additional 4318 constitute a 68% complete red-selected subsample with 20.5 < r(mag) < 21.3. As examples of the strengths of HectoMAP data, we discuss two applications: refined membership of redMaPPer photometrically selected clusters and a test of HSC photometric redshifts. We highlight a remarkable redMaPPer strong lensing system. The comparison of photometric redshifts with spectroscopic redshifts in a dense survey uncovers subtle systematic issues in the photometric redshifts.

ID: 159614
Type: article
Authors: Liu, Ying D.; Chen, Chong; Stevens, Michael L.; Liu, Mingzhe
Abstract: As fundamental parameters of the Sun, the Alfvén radius and angular momentum loss determine how the solar wind changes from sub-Alfvénic to super-Alfvénic and how the Sun spins down. We present an approach to determining the solar wind angular momentum flux based on observations from Parker Solar Probe (PSP). A flux of about 0.15 × 10³⁰ dyn cm sr^-1 near the ecliptic plane and 0.7:1 partition of that flux between the particles and magnetic field are obtained by averaging data from the first four encounters within 0.3 au from the Sun. The angular momentum flux and its particle component decrease with the solar wind speed, while the flux in the field is remarkably constant. A speed dependence in the Alfvén radius is also observed, which suggests a "rugged" Alfvén surface around the Sun. Substantial diving below the Alfvén surface seems plausible only for relatively slow solar wind given the orbital design of PSP. Uncertainties are evaluated based on the acceleration profiles of the same solar wind streams observed at PSP and a radially aligned spacecraft near 1 au. We illustrate that the "angular momentum paradox" raised by Réville et al. can be removed by taking into account the contribution of the alpha particles. The large proton transverse velocity observed by PSP is perhaps inherent in the solar wind acceleration process, where an opposite transverse velocity is produced for the alphas with the angular momentum conserved. Preliminary analysis of some recovered alpha parameters tends to agree with the results.

ID: 159615
Type: article
Authors: Carter, Courtney; Conroy, Charlie; Zaritsky, Dennis; Ting, Yuan-Sen; Bonaca, Ana; Naidu, Rohan P.; Johnson, Benjamin D.; Cargile, Phillip A.; Caldwell, Nelson; Speagle, Joshua; Han, Jiwon Jesse
Abstract: Ancient, very metal-poor (VMP) stars offer a window into the earliest epochs of galaxy formation and assembly. We combine data from the H3 Spectroscopic Survey and Gaia to measure metallicities, abundances of α elements, stellar ages, and orbital properties of a sample of 482 VMP ([Fe/H] 70% of VMP stars near the disk are on prograde orbits and this fraction increases toward lower metallicities. This result is unexpected if metal-poor stars are predominantly accreted from many small systems with no preferred orientation, as such a scenario would imply a mostly isotropic distribution. Furthermore, we find there is some evidence for higher fractions of prograde orbits among stars with lower [α/Fe]. Isochrone-based ages for main-sequence turn-off stars reveal that these VMP stars are uniformly old (≍12 Gyr) irrespective of the α abundance and metallicity, suggesting that the metal-poor population was not born from the same well-mixed gas disk. We speculate that the VMP population has a heterogeneous origin, including both in situ formation in the ancient disk and accretion from a satellite with the same direction of rotation as the ancient disk at early times. Our precisely measured ages for these VMP stars on prograde orbits show that the Galaxy has had a relatively quiescent merging history over most of cosmic time, and implies the angular momentum alignment of the Galaxy has been in place for at least 12 Gyr.

ID: 159616
Type: article
Authors: Aguado, David S.; Belokurov, Vasily; Myeong, G. C.; Evans, N. Wyn; Kobayashi, Chiaki; Sbordone, Luca; Chanamé, Julio; Navarrete, Camila; Koposov, Sergey E.
Abstract: The Gaia Sausage (GS) and the Sequoia represent the major accretion events that formed the stellar halo of the Milky Way. A detailed chemical study of these main building blocks provides a pristine view of the early steps of the Galaxy's assembly. We present the results of the analysis of the UVES high-resolution spectroscopic observations at the 8.2 m VLT of nine Sausage/Sequoia members selected kinematically using Gaia DR2. We season this set of measurements with archival data from Nissen & Schuster and GALAH DR3 (2020). Here, we focus on the neutron-capture process by analyzing Sr, Y, Ba, and Eu behavior. We detect clear enhancement in Eu abundance ([Eu/Fe] ∼ 0.6-0.7) indicative of large prevalence of the r-process in the stellar n-capture makeup. We are also able to trace the evolution of the heavy element production across a wide range of metallicity. The barium to europium changes from a tight, flat sequence with [Ba/Eu] = -0.7 reflecting dominant contribution from exploding massive stars, to a clear upturn at higher iron abundances, betraying the onset of contamination from asymptotic giant branch (AGB) ejecta. Additionally, we discover two clear sequences in the [Fe/H]-[Ba/Fe] plane likely caused by distinct levels of s-process pollution and mixing within the GS progenitor. ^* Based on observations made with Very Large Telescope (VLT) at Paranal Observatory, Chile, under program 0104.B-0487(B).

ID: 159617
Type: article
Authors: Chartab, Nima; Mobasher, Bahram; Shapley, Alice E.; Shivaei, Irene; Sanders, Ryan L.; Coil, Alison L.; Kriek, Mariska; Reddy, Naveen A.; Siana, Brian; Freeman, William R.; Azadi, Mojegan; Barro, Guillermo; Fetherolf, Tara; Leung, Gene; Price, Sedona H.; Zick, Tom
Abstract: Using the near-IR spectroscopy of the MOSFIRE Deep Evolution Field survey, we investigate the role of the local environment in the gas-phase metallicity of galaxies. The local environment measurements are derived from accurate and uniformly calculated photometric redshifts with well-calibrated probability distributions. Based on rest-frame optical emission lines, [N II]λ6584 and Hα, we measure gas-phase oxygen abundances of 167 galaxies at 1.37 ≤ z ≤ 1.7 and 303 galaxies at 2.09 ≤ z ≤ 2.61, located in diverse environments. We find that at z ∼ 1.5, the average metallicity of galaxies in overdensities with M_* ∼ 10^9.8 M_⊙, 10^10.2 M_⊙, and 10^10.8 M_⊙ is higher relative to their field counterparts by 0.094 ± 0.051, 0.068 ± 0.028, and 0.052 ± 0.043 dex, respectively. However, this metallicity enhancement does not exist at higher redshift, z ∼ 2.3, where, compared to the field galaxies, we find 0.056 ± 0.043, 0.056 ± 0.028, and 0.096 ± 0.034 dex lower metallicity for galaxies in overdense environments with M_* ∼ 10^9.8 M_⊙, 10^10.2 M_⊙ and 10^10.7 M_⊙, respectively. Our results suggest that, at 1.37 ≤ z ≤ 2.61, the variation of mass-metallicity relation with local environment is small (, respectively. Our results suggest that, at 1.37 ≤ z ≤ 2.61, the variation of mass-metallicity relation with local environment is small (^* Based on data obtained at the W.M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California, and NASA, and was made possible by the generous financial support of the W.M. Keck Foundation.

ID: 159618
Type: article
Authors: Greco, Johnny P.; van Dokkum, Pieter; Danieli, Shany; Carlsten, Scott G.; Conroy, Charlie
Abstract: We present an in-depth study of surface brightness fluctuations (SBFs) in low-luminosity stellar systems. Using the MIST models, we compute theoretical predictions for absolute SBF magnitudes in the LSST, HST ACS/WFC, and proposed Roman Space Telescope filter systems. We compare our calculations to observed SBF-color relations of systems that span a wide range of age and metallicity. Consistent with previous studies, we find that single-age population models show excellent agreement with observations of low-mass galaxies with 0.5 ≲ g - i ≲ 0.9. For bluer galaxies, the observed relation is better fit by models with composite stellar populations. To study SBF recovery from low-luminosity systems, we perform detailed image simulations in which we inject fully populated model galaxies into deep ground-based images from real observations. Our simulations show that LSST will provide data of sufficient quality and depth to measure SBF magnitudes with precisions of ∼0.2-0.5 mag in ultra-faint $\left({10}^{4}\leqslant {M}_{\star }/{M}_{\odot }\leqslant {10}^{5}\right)$ and low-mass classical (M_⋆ ≤ 10⁷ M_⊙) dwarf galaxies out to ∼4 Mpc and ∼25 Mpc, respectively, within the first few years of its deep-wide-fast survey. Many significant practical challenges and systematic uncertainties remain, including an irreducible "sampling scatter" in the SBFs of ultra-faint dwarfs due to their undersampled stellar mass functions. We nonetheless conclude that SBFs in the new generation of wide-field imaging surveys have the potential to play a critical role in the efficient confirmation and characterization of dwarf galaxies in the nearby universe.

ID: 159619
Type: article
Authors: Lee, Kin Long Kelvin; Loomis, Ryan A.; Burkhardt, Andrew M.; Cooke, Ilsa R.; Xue, Ci; Siebert, Mark A.; Shingledecker, Christopher N.; Remijan, Anthony; Charnley, Steven B.; McCarthy, Michael C.; McGuire, Brett A.
Abstract: We report the discovery of two unsaturated organic species, trans-(E)-cyanovinylacetylene and vinylcyanoacetylene, using the second data release of the GOTHAM deep survey toward TMC-1 with the 100 m Green Bank Telescope. For both detections, we performed velocity stacking and matched filter analyses using Markov Chain Monte Carlo simulations, and for trans-(E)-cyanovinylacetylene, three rotational lines were observed at low signal-to-noise (∼3σ). From this analysis, we derive column densities of 2 × 10¹¹ and 3 × 10¹¹ cm^-2 for vinylcyanoacetylene and trans-(E)-cyanovinylacetylene, respectively, and an upper limit of for vinylcyanoacetylene and trans-(E)-cyanovinylacetylene, respectively, and an upper limit of ¹¹ cm^-2 for trans-(Z)-cyanovinylacetylene. Comparisons with G3//B3LYP semiempirical thermochemical calculations indicate abundances of the [H₃C₅N] isomers are not consistent with their thermodynamic stability, and instead their abundances are mainly driven by dynamics. We provide a discussion on how these species may be formed in TMC-1, with reference to related molecules like vinyl cyanide (CH₂ = CHC ≡ N). As part of this discussion, we performed the same analysis for ethyl cyanide (CH₃CH₂C ≡ N), the hydrogenation product of CH₂ = CHC ≡ N. This analysis provides evidence-at 4.2σ significance-of an upper limit to the column density of = CHC ≡ N. This analysis provides evidence-at 4.2σ significance-of an upper limit to the column density of ¹¹ cm^-2; an order of magnitude lower than previous upper limits toward this source.

ID: 159620
Type: article
Authors: de Vries, Martijn; Romani, Roger W.; Kargaltsev, Oleg; Pavlov, George; Posselt, Bettina; Slane, Patrick; Bucciantini, Niccolo'; Ng, C. -Y; Klingler, Noel
Abstract: We have obtained a deep (670 ks) CXO ACIS image of the remarkable pulsar wind nebula (PWN) of PSR J1709-4429, in four epochs during 2018-2019. Comparison with an archival 2004 data set provides a pulsar proper motion μ = 13 ± 3 mas yr^-1 at a PA of 86° ± 9° (1σ combined statistical and systematic uncertainties), precluding birth near the center of SNR G343.1-2.3. At the pulsar's characteristic age of 17 kyr, the association can be preserved through a combination of progenitor wind, birth kick, and PWN outflow. Associated TeV emission may, however, indicate an explosion in an earlier supernova. Inter-epoch comparison of the X-ray images shows that the PWN is dynamic, but we are unable to conclusively measure flow speeds from blob motion. The pulsar has generated a radio/X-ray wind bubble, and we argue that the PWN's long narrow jets are swept back by shocked pulsar wind venting from this cavity. These jets may trace the polar magnetic field lines of the PWN flow, an interesting challenge for numerical modeling.

ID: 159621
Type: article
Authors: Harrison, Rachel E.; Looney, Leslie W.; Stephens, Ian W.; Li, Zhi-Yun; Teague, Richard; Crutcher, Richard M.; Yang, Haifeng; Cox, Erin G.; Fernández-López, Manuel; Shinnaga, Hiroko
Abstract: While magnetic fields likely play an important role in driving the evolution of protoplanetary disks through angular momentum transport, observational evidence of magnetic fields has only been found in a small number of disks. Although dust continuum linear polarization has been detected in an increasing number of disks, its pattern is more consistent with that from dust scattering than from magnetically aligned grains in the vast majority of cases. Continuum linear polarization from dust grains aligned to a magnetic field can reveal information about the magnetic field's direction, but not its strength. On the other hand, observations of circular polarization in molecular lines produced by Zeeman splitting offer a direct measure of the line-of-sight magnetic field strength in disks. We present upper limits on the net toroidal and vertical magnetic field strengths in the protoplanetary disk AS 209 derived from Zeeman splitting observations of the CN 2-1 line. The 3σ upper limit on the net line-of-sight magnetic field strength in AS 209 is 5.0 mG on the redshifted side of the disk and 4.2 mG on the blueshifted side of the disk. Given the disk's inclination angle, we set a 3σ upper limit on the net toroidal magnetic field strength of 8.7 and 7.3 mG for the red and blue sides of the disk, respectively, and 6.2 and 5.2 mG on the net vertical magnetic field on the red and blue sides of the disk. If magnetic disk winds are a significant mechanism of angular momentum transport in the disk, magnetic fields of a strength close to the upper limits would be sufficient to drive accretion at the rate previously inferred for regions near the protostar.

ID: 159622
Type: article
Authors: Fausnaugh, M. M.; Vallely, P. J.; Kochanek, C. S.; Shappee, B. J.; Stanek, K. Z.; Tucker, M. A.; Ricker, George R.; Vanderspek, Roland; Latham, David W.; Seager, S.; Winn, Joshua N.; Jenkins, Jon M.; Berta-Thompson, Zachory K.; Daylan, Tansu; Doty, John P.; Fűrész, Gábor; Levine, Alan M.; Morris, Robert; Pál, András; Sha, Lizhou; Ting, Eric B.; Wohler, Bill
Abstract: We present the early-time light curves of Type Ia supernovae (SNe Ia) observed in the first six sectors of Transiting Exoplanet Survey Satellite (TESS) data. Ten of these SNe were discovered by ASAS-SN, seven by ATLAS, six by ZTF, and one by Gaia. For nine of these objects with sufficient dynamic range (>3.0 mag from detection to peak), we fit power-law models and searched for signatures of companion stars. We found a diversity of early-time light-curve shapes, although most of our sources are consistent with fireball models where the flux increases as ∝t². Three SNe displayed a flatter rise with flux ∝t. We did not find any obvious evidence for additional structures, such as multiple power-law components, in the early rising light curves. For assumptions about the SN properties and the observer viewing angle (ejecta mass of 1.4 M_⊙, expansion velocity of 10⁴ km s^-1, opacity of 0.2 cm² g^-1, and viewing angle of 45°) and a further assumption that any companion stars would be in Roche lobe overflow, it is possible to place upper limits on the radii of any companion stars. Six of the nine SNe had complete coverage of the early-time light curves, and we placed upper limits on the radii of companion stars of ≲32 R_⊙ for these SNe, ≲20 R_⊙ for five of the six, and ≲4 R_⊙ for two of the six. The small sample size did not allow us to put limits on the occurrence rate of companion stars in the progenitors of SNe Ia. However, we expect that TESS observed enough SNe in its two-year primary mission (26 sectors) to either detect the signature of a large companion (R > 20 R_⊙) or constrain the occurrence rate of such systems, at least for the fiducial SN properties adopted here. We also show that TESS is capable of detecting emission from a 1 R_⊙ companion for an SN Ia within 50 Mpc and has a reasonable chance of doing so after about six years.

ID: 159623
Type: article
Authors: Pegues, Jamila; Czekala, Ian; Andrews, Sean M.; Öberg, Karin I.; Herczeg, Gregory J.; Bergner, Jennifer B.; Ilsedore Cleeves, L.; Guzmán, Viviana V.; Huang, Jane; Long, Feng; Teague, Richard; Wilner, David J.
Abstract: In this era of Gaia and ALMA, dynamical stellar mass measurements, derived from spatially and spectrally resolved observations of the Keplerian rotation of circumstellar disks, provide benchmarks that are independent of observations of stellar characteristics and their uncertainties. These benchmarks can then be used to validate and improve stellar evolutionary models, the latter of which can lead to both imprecise and inaccurate mass predictions for pre-main-sequence, low-mass (≤0.5 M_⊙) stars. We present the dynamical stellar masses derived from disks around three M stars (FP Tau, J0432+1827, and J1100-7619) using ALMA observations of ¹²CO (J = 2-1) and ¹³CO (J = 2-1) emission. These are the first dynamical stellar mass measurements for J0432+1827 and J1100-7619 (0.192 ± 0.005 M_⊙ and 0.461 ± 0.057 M_⊙, respectively) and the most precise measurement for FP Tau (0.395 ± 0.012 M_⊙). Fiducial stellar evolutionary model tracks, which do not include any treatment of magnetic activity, agree with the dynamical stellar mass measurement of J0432+1827 but underpredict the mass by ∼60% for FP Tau and by ∼80% for J1100-7619. Possible explanations for the underpredictions include inaccurate assumptions of stellar effective temperature, undetected binarity for J1100-7619, and that fiducial stellar evolutionary models are not complex enough to represent these stars. In the former case, the stellar effective temperatures would need to be increased by amounts ranging from ∼40 to ∼340 K to reconcile the fiducial stellar evolutionary model predictions with the dynamically measured masses. In the latter case, we show that the dynamical masses can be reproduced using results from stellar evolutionary models with starspots, which incorporate fractional starspot coverage to represent the manifestation of magnetic activity. Folding in low-mass M stars from the literature and assuming that the stellar effective temperatures are imprecise but accurate, we find tentative evidence of a relationship between fractional starspot coverage and observed effective temperature for these young, cool stars.

ID: 159624
Type: article
Authors: Alt, Andrew; Myers, Clayton E.; Ji, Hantao; Jara-Almonte, Jonathan; Yoo, Jongsoo; Bose, Sayak; Goodman, Aaron; Yamada, Masaaki; Kliem, Bernhard; Savcheva, Antonia
Abstract: Coronal mass ejections (CMEs) occur when long-lived magnetic flux ropes (MFRs) anchored to the solar surface destabilize and erupt away from the Sun. This destabilization is often described in terms of an ideal magnetohydrodynamic instability called the torus instability. It occurs when the external magnetic field decreases sufficiently fast such that its decay index, ${n}_{}=-z\,\partial (\mathrm{ln}{B}_{})/\partial z$ , is larger than a critical value, $n> {n}_{\mathrm{cr}}^{}$ , where ${n}_{\mathrm{cr}}^{}=1.5$ for a full, large aspect ratio torus. However, when this is applied to solar MFRs, a range of conflicting values for ${n}_{\mathrm{cr}}^{}$ is found in the literature. To investigate this discrepancy, we have conducted laboratory experiments on arched, line-tied flux ropes and applied a theoretical model of the torus instability. Our model describes an MFR as a partial torus with foot points anchored in a conducting surface and numerically calculates various magnetic forces on it. This calculation yields better predictions of ${n}_{\mathrm{cr}}^{}$ that take into account the specific parameters of the MFR. We describe a systematic methodology to properly translate laboratory results to their solar counterparts, provided that the MFRs have a sufficiently small edge safety factor or, equivalently, a large enough twist. After this translation, our model predicts that ${n}_{\mathrm{cr}}^{}$ in solar conditions falls near ${n}_{\mathrm{cr}}^{\mathrm{solar}}\sim 0.9$ and within a larger range of ${n}_{\mathrm{cr}}^{\mathrm{solar}}\sim (0.7,1.2)$ , depending on the parameters. The methodology of translating laboratory MFRs to their solar counterparts enables quantitative investigations of CME initiation through laboratory experiments. These experiments allow for new physics insights that are required for better predictions of space weather events but are difficult to obtain otherwise.

ID: 159625
Type: article
Authors: Ma, Jingzhe; Maksym, W. Peter; Fabbiano, G.; Elvis, Martin; Storchi-Bergmann, Thaisa; Karovska, Margarita; Wang, Junfeng; Travascio, Andrea
Abstract: We present spatially resolved Baldwin-Phillips-Terlevich (BPT) mapping of the extended narrow-line regions (ENLRs) of seven nearby Seyfert 2 galaxies, using Hubble Space Telescope narrowband filter imaging. We construct the BPT diagrams using ≤0"1 resolution emission line images of [O III] λ5007, Hα, [S II] λλ6717, 6731, and Hβ. By mapping these diagnostic lines according to the BPT classification, we dissect the ENLR into Seyfert, low-ionization nuclear emission-line (LINER), and star-forming regions. The nucleus and ionization cones are dominated by Seyfert-type emission, which can be interpreted as predominantly photoionization by the active galactic nucleus (AGN). The Seyfert nucleus and ionization cones transition to and are surrounded by a LINER cocoon, extending up to ∼250 pc in thickness. The ubiquity of the LINER cocoon in Seyfert 2 galaxies suggests that the circumnuclear regions are not necessarily Seyfert-type, and LINER activity plays an important role in Seyfert 2 galaxies. We demonstrate that spatially resolved diagnostics are crucial to understanding the excitation mechanisms in different regions and the AGN-host galaxy interactions.

ID: 159626
Type: article
Authors: Golden-Marx, Emmet; Blanton, E. L.; Paterno-Mahler, R.; Brodwin, M.; Ashby, M. L. N.; Moravec, E.; Shen, L.; Lemaux, B. C.; Lubin, L. M.; Gal, R. R.; Tomczak, A. R.
Abstract: The shape of bent, double-lobed radio sources requires a dense gaseous medium. Bent sources can therefore be used to identify galaxy clusters and characterize their evolutionary history. By combining radio observations from the Very Large Array Faint Images of the Radio Sky at Twenty centimeters (VLA FIRST) survey with optical and infrared imaging of 36 red sequence selected cluster candidates from the high-z Clusters Occupied by Bent Radio AGN (COBRA) survey (0.35 < z < 2.2), we find that radio sources with narrower opening angles reside in richer clusters, indicating that the cluster environment impacts radio morphology. Within these clusters, we determine 55.5% of our radio host galaxies are brightest cluster galaxies (BCGs) and that the remainder are associated with other luminous galaxies. The projected separations between the radio sources and cluster centers and the sizes of the opening angles of bent sources follow similar distributions for BCG and non-BCG host populations, suggesting that COBRA host galaxies are either BCGs or galaxies that may evolve into BCGs. By measuring the orientation of the radio sources relative to the cluster centers, we find between 30% and 42% of COBRA bent sources are outgoing and have passed through the cluster center, while between 8% and 58% of COBRA bent sources are infalling. Although these sources typically do not follow directly radial paths, the large population of outgoing sources contrasts what is observed in low-z samples of bent sources and may indicate that the intracluster medium is less dense in these high-z clusters.

ID: 159627
Type: article
Authors: Chen, Bin; Battaglia, Marina; Krucker, Säm; Reeves, Katharine K.; Glesener, Lindsay
Abstract: Nonthermal sources located above bright flare arcades, referred to as the "above-the-loop-top" sources, have been often suggested as the primary electron acceleration site in major solar flares. The X8.2 limb flare on 2017 September 10 features such an above-the-loop-top source, which was observed in both microwaves and hard X-rays (HXRs) by the Expanded Owens Valley Solar Array and the Reuven Ramaty High Energy Solar Spectroscopic Imager, respectively. By combining the microwave and HXR imaging spectroscopy observations with multifilter extreme ultraviolet and soft X-ray imaging data, we derive the coronal magnetic field and energetic electron distribution of the source over a broad energy range from 6.0. Temporally resolved analysis suggests that the electron distribution above the break energy rapidly hardens with the spectral index decreasing from >20 to ∼6.0 within 20 s, or less than ∼10 Alfvén crossing times in the source. These results provide strong support for the above-the-loop-top source as the primary site where an ongoing bulk acceleration of energetic electrons is taking place very early in the flare energy release.

ID: 159628
Type: article
Authors: Shi, Chen; Zhao, Jinsong; Huang, Jia; Wang, Tieyan; Wu, Dejin; Chen, Yu; Hu, Qiang; Kasper, Justin C.; Bale, Stuart D.
Abstract: Small-scale flux ropes (SFRs) are common in the interplanetary environment. However, previous identification procedures generally discard SFRs with medium and high Alfvénicity, which are thought to be Alfvénic waves or Alfvénic structures. This paper first identifies an SFR event with medium Alfvénicity in the inner heliosphere (at ∼0.2 au) using Parker Solar Probe measurements. We find Alfvénic waves that arise inside SFR based on high correlations between the magnetic field and velocity fluctuations. We also observe quasi-monochromatic electromagnetic waves with frequencies f that are usually larger than the local proton cyclotron frequency at the leading and trailing edges of this SFR. These waves are well explained by the outward-propagating ion-cyclotron waves, which have wave frequencies ∼0.03-0.3 Hz and wavelengths ∼60-2000 km in the plasma frame. Moreover, we show that the power spectral density of the magnetic field in SFR middle region follows the power-law distribution, where the spectral index changes from -1.5 (f ≲ 1 Hz) to -3.3 (f ≳ 1 Hz). These findings would motivate developing an automated program to identify SFRs with medium and high Alfvénicity from Alfvénic waves/structures.

ID: 159629
Type: article
Authors: Reichardt, C. L.; Patil, S.; Ade, P. A. R.; Anderson, A. J.; Austermann, J. E.; Avva, J. S.; Baxter, E.; Beall, J. A.; Bender, A. N.; Benson, B. A.; Bianchini, F.; Bleem, L. E.; Carlstrom, J. E.; Chang, C. L.; Chaubal, P.; Chiang, H. C.; Chou, T. L.; Citron, R.; Moran, C. Corbett; Crawford, T. M.; Crites, A. T.; de Haan, T.; Dobbs, M. A.; Everett, W.; Gallicchio, J.; George, E. M.; Gilbert, A.; Gupta, N.; Halverson, N. W.; Harrington, N.; Henning, J. W.; Hilton, G. C.; Holder, G. P.; Holzapfel, W. L.; Hrubes, J. D.; Huang, N.; Hubmayr, J.; Irwin, K. D.; Knox, L.; Lee, A. T.; Li, D.; Lowitz, A.; Luong-Van, D.; McMahon, J. J.; Mehl, J.; Meyer, S. S.; Millea, M.; Mocanu, L. M.; Mohr, J. J.; Montgomery, J.; Nadolski, A.; Natoli, T.; Nibarger, J. P.; Noble, G.; Novosad, V.; Omori, Y.; Padin, S.; Pryke, C.; Ruhl, J. E.; Saliwanchik, B. R.; Sayre, J. T.; Schaffer, K. K.; Shirokoff, E.; Sievers, C.; Smecher, G.; Spieler, H. G.; Staniszewski, Z.; Stark, Antony A.; Tucker, C.; Vanderlinde, K.; Veach, T.; Vieira, J. D.; Wang, G.; Whitehorn, N.; Williamson, R.; Wu, W. L. K.; Yefremenko, V.
Abstract: We report new measurements of millimeter-wave power spectra in the angular multipole range 2000 ≤ ℓ ≤ 11,000 (angular scales $5^{\prime} >rsim \theta >rsim 1^{\prime} $ ). By adding 95 and 150 GHz data from the low-noise 500 deg² SPTpol survey to the SPT-SZ three-frequency 2540 deg² survey, we substantially reduce the uncertainties in these bands. These power spectra include contributions from the primary cosmic microwave background, cosmic infrared background, radio galaxies, and thermal and kinematic Sunyaev-Zel'dovich (SZ) effects. The data favor a thermal SZ (tSZ) power at 143 GHz of ${D}_{3000}^{\mathrm{tSZ}}=3.42\pm 0.54\,\,\mu {{\rm{K}}}^{2}$ and a kinematic SZ (kSZ) power of ${D}_{3000}^{\mathrm{kSZ}}=3.0\pm 1.0\,\,\mu {{\rm{K}}}^{2}$ . This is the first measurement of kSZ power at ≥3σ. However, different assumptions about the CIB or SZ models can reduce the significance down to 2.4σ in the worst case. We study the implications of the measured kSZ power for the epoch of reionization under the Calabrese et al. model for the kSZ power spectrum and find the duration of reionization to be ${\rm{\Delta }}{z}_{\mathrm{re}}={1.1}_{-0.7}^{+1.6}$ ( ${\rm{\Delta }}{z}_{\mathrm{re}} survey, we substantially reduce the uncertainties in these bands. These power spectra include contributions from the primary cosmic microwave background, cosmic infrared background, radio galaxies, and thermal and kinematic Sunyaev-Zel'dovich (SZ) effects. The data favor a thermal SZ (tSZ) power at 143 GHz of ${D}_{3000}^{\mathrm{tSZ}}=3.42\pm 0.54\,\,\mu {{\rm{K}}}^{2}$ and a kinematic SZ (kSZ) power of ${D}_{3000}^{\mathrm{kSZ}}=3.0\pm 1.0\,\,\mu {{\rm{K}}}^{2}$ . This is the first measurement of kSZ power at ≥3σ. However, different assumptions about the CIB or SZ models can reduce the significance down to 2.4σ in the worst case. We study the implications of the measured kSZ power for the epoch of reionization under the Calabrese et al. model for the kSZ power spectrum and find the duration of reionization to be ${\rm{\Delta }}{z}_{\mathrm{re}}={1.1}_{-0.7}^{+1.6}$ ( ${\rm{\Delta }}{z}_{\mathrm{re}} survey, we substantially reduce the uncertainties in these bands. These power spectra include contributions from the primary cosmic microwave background, cosmic infrared background, radio galaxies, and thermal and kinematic Sunyaev-Zel'dovich (SZ) effects. The data favor a thermal SZ (tSZ) power at 143 GHz of ${D}_{3000}^{\mathrm{tSZ}}=3.42\pm 0.54\,\,\mu {{\rm{K}}}^{2}$ and a kinematic SZ (kSZ) power of ${D}_{3000}^{\mathrm{kSZ}}=3.0\pm 1.0\,\,\mu {{\rm{K}}}^{2}$ . This is the first measurement of kSZ power at ≥3σ. However, different assumptions about the CIB or SZ models can reduce the significance down to 2.4σ in the worst case. We study the implications of the measured kSZ power for the epoch of reionization under the Calabrese et al. model for the kSZ power spectrum and find the duration of reionization to be ${\rm{\Delta }}{z}_{\mathrm{re}}={1.1}_{-0.7}^{+1.6}$ ( ${\rm{\Delta }}{z}_{\mathrm{re}}²) and relaxes to ${\rm{\Delta }}{z}_{\mathrm{re}}< 5.2$ if the homogeneous kSZ power is decreased by the same amount.

ID: 159630
Type: article
Authors: Stassun, Keivan G.; Torres, Guillermo
Abstract: Previous analyses of various standard candles observed by the Gaia satellite have reported statistically significant systematics in the parallaxes that have improved from ∼250 μas in the first data release (DR1) to 50-80 μas in the second data release (DR2). Here we examine the parallaxes newly reported in the Gaia early third data release (EDR3) using the same sample of benchmark eclipsing binaries (EBs) we used to assess the DR1 and DR2 parallaxes. We find a mean offset of -37 ± 20 μas (Gaia - EB), which decreases to -15 ± 18 μas after applying the corrections recommended by the Gaia Mission team; global systematics in the Gaia parallaxes have clearly improved and are no longer statistically significant for the EB sample, which spans 5 ≲ G ≲ 12 in brightness and 0.03-3 kpc in distance. We also find that the Renormalized Unit Weight Error (RUWE) goodness-of-fit statistic reported in Gaia DR3 is highly sensitive to unresolved companions (tertiaries in the case of our EB sample) as well as to photocenter motion of the binaries themselves. RUWE is nearly perfectly correlated (r² = 0.82) with photocenter motions down to ≲0.1 mas, and surprisingly this correlation exists entirely within the nominal "good" RUWE range of 1.0-1.4. This suggests that RUWE values even slightly greater than 1.0 may signify unresolved binaries in Gaia, and that the RUWE value can serve as a quantitative predictor of the photocenter motion.

ID: 159631
Type: article
Authors: Liu, F. K.; Cao, C. Y.; Abramowicz, M. A.; Wielgus, Maciek; Cao, R.; Zhou, Z. Q.
Abstract: Elliptical accretion disk models for tidal disruption events (TDEs) have been recently proposed and independently developed by two groups. Although these two models are characterized by a similar geometry, their physical properties differ considerably. In this paper, we further investigate the properties of the elliptical accretion disk of the nearly uniform distribution of eccentricity within the disk plane. Our results show that the elliptical accretion disks have distinctive hydrodynamic structures and spectral energy distributions, associated with TDEs. The soft X-ray photons generated at pericenter and nearby are trapped in the disk and advected around the ellipse because of large electron scattering opacity. They are absorbed and reprocessed into emission lines and low-frequency continuum via recombination and bremsstrahlung emission. Because of the rapid increase of bound-free and free-free opacities with radius, the low-frequency continuum photons become trapped in the disk at large radius and are advected through apocenter and back to the photon-trapping radius. Elliptical accretion disks predict sub-Eddington luminosities and emit mainly at the photon-trapping radius of thousands of Schwarzschild radii with a blackbody spectrum of nearly single temperature of typically about 3 × 10⁴ K. Because of the self-regulation, the photon-trapping radius expands and contracts following the rise and fall of accretion rate. The radiation temperature is nearly independent of BH mass and accretion rate and varies weakly with the stellar mass and the viscosity parameter. Our results are well consistent with the observations of optical/UV TDEs.

ID: 159632
Type: article
Authors: Yi, Huili; Wang, Junfeng; Shu, Xinwen; Fabbiano, Giuseppina; Pappalardo, Cirino; Wang, Chen; Yu, Hanbo
Abstract: We present imaging and spectral analysis of the combined ∼48 ks Chandra observations of Seyfert 2 galaxy NGC 4388. Compared with previous studies, three prominent extended X-ray structures around the nucleus on a kiloparsec-scale are well imaged, allowing an in-depth spatially resolved study. Both the extended hard continuum (4-6 keV) and the Fe Kα line (6.2-6.7 keV) show similar morphology, consistent with a scenario where the ionizing emission from the nucleus is reprocessed by circumnuclear cold gas, resulting in a weak reflection continuum and an associated neutral Fe Kα line. This has been seen in other Compton-thick active galactic nuclei (AGN), but NGC 4388 is one of the rare cases with a lower column density (N_H ²⁴ cm^-2) along the line of sight. Significant differences in equivalent width of the Fe Kα emission line (up to a factor of 3) are found for the nuclear and extended regions. Such a difference could be ascribed to different column densities or scattering angles with respect to the line of sight, rather than variations in iron abundances. The northeast and west extended structures appear to be aligned with the larger-scale galactic disk and dust lane in the HST V - H color map, and are located at the peak of molecular gas distribution. The morphology of remaining extended features likely traces edges of a known radio jet, indicating that the outflow at the kiloparsec-scale may have compressed the interstellar gas and produced clumps working as the reflector to enhance line emission. In addition, using [O IV] emission as a proxy of the AGN intrinsic luminosity, we find that both of the extended Fe Kα emission and reflection continuum are linearly correlated with the [O IV] luminosity, which indicates a connection between the central AGN and the extended emission.

ID: 159633
Type: article
Authors: Heuer, Keri; Foster, Adam R.; Smith, Randall
Abstract: Two new high-resolution X-ray spectroscopy missions, XRISM and Athena, will observe deeper and with higher X-ray resolution than ever before possible. Interpreting these new X-ray spectra will require understanding the impact that uncertainties on fundamental atomic quantities such as collisional cross sections, transition rates, and wavelengths have on spectral models. As millions of values are required to generate even a simple model of an optically thin hot plasma, most such rates exist only as theoretical calculations. We have developed methods to estimate the uncertainty in the final spectral calculations based on published experimental data and plausible approximations to the uncertainties in the underlying atomic data. We present an extension to the pyatomdb code which implements these methods and investigate the sensitivity of selected strong diagnostic lines in the X-ray bandpass (0.3-12 keV).

ID: 159634
Type: article
Authors: Shan, Yutong; Yee, Jennifer C.; Bailey, Vanessa P.; Close, Laird M.; Hinz, Phil M.; Males, Jared R.; Morzinski, Katie M.
Abstract: We present limits on the lens flux of OGLE-2007-BLG-224 based on MagAO imaging taken seven years after the microlensing event. At the time of the observations, the lens should have been separated from the microlensing source by 292 mas. However, no new sources are detected with MagAO. We place an upper limit on the lens flux of H > 20.57. This measurement supports the conclusion of Gould et al. that the lens in this event should be a brown dwarf. This is the first test of a prediction based on the terrestrial microlens parallax effect and the first AO confirmation of a substellar/dark microlens.

ID: 159635
Type: article
Authors: Suzuki, Tomoko L.; Onodera, Masato; Kodama, Tadayuki; Daddi, Emanuele; Hayashi, Masao; Koyama, Yusei; Shimakawa, Rhythm; Smail, Ian; Sobral, David; Tacchella, Sandro; Tanaka, Ichi
Abstract: We conducted submillimeter observations with the Atacama Large Millimeter/submillimeter Array (ALMA) of star-forming galaxies at z ∼ 3.3, whose gas-phase metallicities have been measured previously. We investigated the dust and gas contents of the galaxies at z ∼ 3.3 and studied the interaction of galaxies with their circumgalactic or intergalactic medium at this epoch by probing their gas mass fractions and gas-phase metallicities. Single-band dust continuum emission tracing dust mass and the relation between the gas-phase metallicity and gas-to-dust mass ratio were used to estimate the gas masses. The estimated gas mass fractions and depletion timescales are f_gas= 0.20-0.75 and t_dep= 0.09-1.55 Gyr. Although the galaxies appear to be tightly distributed around the star-forming main sequence at z ∼ 3.3, both quantities show a wider spread at a fixed stellar mass than expected from the scaling relation, suggesting a large diversity of fundamental gas properties in star-forming galaxies that apparently lie on the main sequence. When we compared gas mass fraction and gas-phase metallicity in star-forming galaxies at z ∼ 3.3 and at lower redshifts, star-forming galaxies at z ∼ 3.3 appear to be more metal poor than local galaxies with similar gas mass fractions. Using the gas regulator model to interpret this offset, we find that this can be explained by a higher mass-loading factor, suggesting that the mass-loading factor in outflows increases at earlier cosmic times.

ID: 159636
Type: article
Authors: Neufeld, David A.; Menten, Karl M.; Durán, Carlos; Güsten, Rolf; Kaufman, Michael J.; Kraus, Alex; Mazumdar, Parichay; Melnick, Gary J.; Ortiz-León, Gisela N.; Wiesemeyer, Helmut; Wyrowski, Friedrich
Abstract: Following up on our discovery of terahertz water masers, reported in 2017, we report two further detections of water maser emission at frequencies above 1 THz. Using the GREAT instrument on SOFIA, we have detected emission in the 1.296411 THz 8₂₇ - 7₃₄ transition of water toward two additional oxygen-rich evolved stars, omicron Ceti (Mira) and R Crateris, and obtained an upper limit on the 1.296 THz line emission from U Orionis. Toward these three sources, and toward the red supergiant star VY Canis Majorae from which 1.296 THz line emission was reported previously, we have also observed several lower-frequency (sub)millimeter water maser transitions using the APEX 12 m telescope along with the 22 GHz transition using the Effelsberg 100 m telescope. We have used a simple model to analyze the multitransition data thereby obtained. Adopting, as a prior, independent literature estimates of the mass-loss rates in these four sources and in W Hydrae, we infer water abundances in a remarkably narrow range: n(H₂O)/n(H₂) = 1.4-2.5 × 10^-4. For o Cet, VY CMa, and W Hya, the model is successful in predicting the maser line fluxes to within a typical factor ∼1.6-3. For R Crt and U Ori, the model is less successful, with typical line flux predictions lying an order of magnitude above or below the observations; such discrepancies are perhaps unsurprising given the exponential nature of maser amplification. ^* GREAT, the German REceiver for Astronomy at Terahertz frequencies, is a development by the MPI für Radioastronomie and the KOSMA/Universität zu Köln, in cooperation with the DLR Institut für Optische Sensorsysteme.

ID: 159637
Type: article
Authors: Bicep/Keck; Ade, P. A. R.; Ahmed, Z.; Amiri, M.; Barkats, D.; Basu Thakur, R.; Bischoff, C. A.; Bock, J. J.; Boenish, H.; Bullock, E.; Buza, V.; Cheshire, J. R.; Connors, J.; Cornelison, J.; Crumrine, M.; Cukierman, A.; Dierickx, Marion; Duband, L.; Fatigoni, S.; Filippini, J. P.; Fliescher, S.; Goeckner-Wald, N.; Grayson, J.; Hall, G.; Halpern, M.; Harrison, S.; Henderson, S.; Hildebrandt, S. R.; Hilton, G. C.; Hubmayr, J.; Hui, H.; Irwin, K. D.; Kang, J.; Karkare, K. S.; Karpel, E.; Keating, B. G.; Kefeli, S.; Kernasovskiy, S. A.; Kovac, J. M.; Kuo, C. L.; Lau, K.; Leitch, E. M.; Megerian, K. G.; Moncelsi, L.; Namikawa, T.; Netterfield, C. B.; Nguyen, H. T.; O'Brient, R.; Ogburn, R. W.; Palladino, S.; Prouve, T.; Pryke, C.; Racine, B.; Reintsema, C. D.; Richter, S.; Schillaci, A.; Schmitt, B. L.; Schwarz, R.; Sheehy, C. D.; Soliman, A.; Germaine, T. St; Steinbach, B.; Sudiwala, R. V.; Teply, G.; Thompson, K. L.; Tolan, J. E.; Tucker, C.; Turner, A. D.; Umilta, C.; Vieregg, A. G.; Wandui, A.; Weber, A. C.; Wiebe, D. V.; Willmert, J.; Wong, C. L.; Wu, W. L. K.; Yang, H.; Yoon, K. W.; Young, E.; Yu, C.; Zeng, L.; Zhang, C.; BICEP/Keck Collaboration
Abstract: We present a search for axionlike polarization oscillations in the cosmic microwave background (CMB) with observations from the Keck Array. A local axion field induces an all-sky, temporally sinusoidal rotation of CMB polarization. A CMB polarimeter can thus function as a direct-detection experiment for axionlike dark matter. We develop techniques to extract an oscillation signal. Many elements of the method are generic to CMB polarimetry experiments and can be adapted for other datasets. As a first demonstration, we process data from the 2012 observing season to set upper limits on the axion-photon coupling constant in the mass range 10^-21- 10^-18 eV , which corresponds to oscillation periods on the order of hours to months. We find no statistically significant deviations from the background model. For periods larger than 24 hr (mass m eV , which corresponds to oscillation periods on the order of hours to months. We find no statistically significant deviations from the background model. For periods larger than 24 hr (mass m ^-20 eV ), the median 95% confidence upper limit is equivalent to a rotation amplitude of 0.68°, which constrains the axion-photon coupling constant to g_{ϕ γ}^-11 GeV^-1)m /(10^-21 eV ) , if axionlike particles constitute all of the dark matter. The constraints can be improved substantially with data already collected by the BICEP series of experiments. Current and future CMB polarimetry experiments are expected to achieve sufficient sensitivity to rule out unexplored regions of the axion parameter space.

ID: 159638
Type: article
Authors: Porredon, A.; Crocce, M.; Fosalba, P.; Elvin-Poole, J.; Carnero Rosell, A.; Cawthon, R.; Eifler, T. F.; Fang, X.; Ferrero, I.; Krause, E.; MacCrann, N.; Weaverdyck, N.; Abbott, T. M. C.; Aguena, M.; Allam, S.; Amon, A.; Avila, S.; Bacon, D.; Bertin, E.; Bhargava, S.; Bridle, S. L.; Brooks, D.; Carrasco Kind, M.; Carretero, J.; Castander, F. J.; Choi, A.; Costanzi, M.; da Costa, L. N.; Pereira, M. E. S.; De Vicente, J.; Desai, S.; Diehl, H. T.; Doel, P.; Drlica-Wagner, A.; Eckert, K.; Ferté, A.; Flaugher, B.; Frieman, J.; García-Bellido, J.; Gaztanaga, E.; Gerdes, D. W.; Giannantonio, T.; Gruen, D.; Gruendl, R. A.; Gschwend, J.; Gutierrez, G.; Hartley, W. G.; Hinton, S. R.; Hollowood, D. L.; Honscheid, K.; Hoyle, B.; James, David J.; Jarvis, M.; Kuehn, K.; Kuropatkin, N.; Maia, M. A. G.; Marshall, J. L.; Menanteau, F.; Miquel, R.; Morgan, R.; Palmese, A.; Pandey, S.; Paz-Chinchón, F.; Plazas, A. A.; Rodriguez-Monroy, M.; Roodman, A.; Samuroff, S.; Sanchez, E.; Scarpine, V.; Serrano, S.; Sevilla-Noarbe, I.; Smith, M.; Soares-Santos, M.; Suchyta, E.; Swanson, M. E. C.; Tarle, G.; To, C.; Varga, T. N.; Weller, J.; Wilkinson, R. D.; DES Collaboration
Abstract: We investigate potential gains in cosmological constraints from the combination of galaxy clustering and galaxy-galaxy lensing by optimizing the lens galaxy sample selection using information from Dark Energy Survey (DES) Year 3 data and assuming the DES Year 1 METACALIBRATION sample for the sources. We explore easily reproducible selections based on magnitude cuts in i -band as a function of (photometric) redshift, z_phot, and benchmark the potential gains against those using the well-established REDMAGIC [E. Rozo et al., Mon. Not. R. Astron. Soc. 461, 1431 (2016), 10.1093/mnras/stw1281] sample. We focus on the balance between density and photometric redshift accuracy, while marginalizing over a realistic set of cosmological and systematic parameters. Our optimal selection, the MAGLIM sample, satisfies i , and benchmark the potential gains against those using the well-established REDMAGIC [E. Rozo et al., Mon. Not. R. Astron. Soc. 461, 1431 (2016), 10.1093/mnras/stw1281] sample. We focus on the balance between density and photometric redshift accuracy, while marginalizing over a realistic set of cosmological and systematic parameters. Our optimal selection, the MAGLIM sample, satisfies i _phot+18 and has ∼30 % wider redshift distributions but ∼3.5 times more galaxies than REDMAGIC. Assuming a w CDM model (i.e. with a free parameter for the dark energy equation of state) and equivalent scale cuts to mitigate nonlinear effects, this leads to 40% increase in the figure of merit for the pair combinations of Ω_m, w , and σ₈, and gains of 16% in σ₈, 10% in Ω_m, and 12% in w . Similarly, in Λ CDM , we find an improvement of 19% and 27% on σ₈ and Ω_m, respectively. We also explore flux-limited samples with a flat magnitude cut finding that the optimal selection, i <22.2 , has ∼7 times more galaxies and ∼20 % wider redshift distributions compared to MAGLIM, but slightly worse constraints. We show that our results are robust with respect to the assumed galaxy bias and photometric redshift uncertainties with only moderate further gains from increased number of tomographic bins or the inclusion of bin cross-correlations, except in the case of the flux-limited sample, for which these gains are more significant.

ID: 159640
Type: article
Authors: Muir, J.; Baxter, E.; Miranda, V.; Doux, C.; Ferté, A.; Leonard, C. D.; Huterer, D.; Jain, B.; Lemos, P.; Raveri, M.; Nadathur, S.; Campos, A.; Chen, A.; Dodelson, S.; Elvin-Poole, J.; Lee, S.; Secco, L. F.; Troxel, M. A.; Weaverdyck, N.; Zuntz, J.; Brout, Dillon; Choi, A.; Crocce, M.; Davis, T. M.; Gruen, D.; Krause, E.; Lidman, C.; MacCrann, N.; Möller, A.; Prat, J.; Ross, A. J.; Sako, M.; Samuroff, S.; Sánchez, C.; Scolnic, D.; Zhang, B.; Abbott, T. M. C.; Aguena, M.; Allam, S.; Annis, J.; Avila, S.; Bacon, D.; Bertin, E.; Bhargava, S.; Bridle, S. L.; Brooks, D.; Burke, D. L.; Carnero Rosell, A.; Carrasco Kind, M.; Carretero, J.; Cawthon, R.; Costanzi, M.; da Costa, L. N.; Pereira, M. E. S.; Desai, S.; Diehl, H. T.; Dietrich, J. P.; Doel, P.; Estrada, J.; Everett, S.; Evrard, A. E.; Ferrero, I.; Flaugher, B.; Frieman, J.; García-Bellido, J.; Giannantonio, T.; Gruendl, R. A.; Gschwend, J.; Gutierrez, G.; Hinton, S. R.; Hollowood, D. L.; Honscheid, K.; Hoyle, B.; James, David J.; Jeltema, T.; Kuehn, K.; Kuropatkin, N.; Lahav, O.; Lima, M.; Maia, M. A. G.; Menanteau, F.; Miquel, R.; Morgan, R.; Myles, J.; Palmese, A.; Paz-Chinchón, F.; Plazas, A. A.; Romer, A. K.; Roodman, A.; Sanchez, E.; Scarpine, V.; Serrano, S.; Sevilla-Noarbe, I.; Smith, M.; Suchyta, E.; Swanson, M. E. C.; Tarle, G.; Thomas, D.; To, C.; Tucker, D. L.; Varga, T. N.; Weller, J.; Wilkinson, R. D.; DES Collaboration
Abstract: We analyze Dark Energy Survey (DES) data to constrain a cosmological model where a subset of parameters-focusing on Ω_m-are split into versions associated with structure growth (e.g., Ω_m^grow) and expansion history (e.g., Ω_m^geo). Once the parameters have been specified for the Λ CDM cosmological model, which includes general relativity as a theory of gravity, it uniquely predicts the evolution of both geometry (distances) and the growth of structure over cosmic time. Any inconsistency between measurements of geometry and growth could therefore indicate a breakdown of that model. Our growth-geometry split approach therefore serves both as a (largely) model-independent test for beyond-Λ CDM physics, and as a means to characterize how DES observables provide cosmological information. We analyze the same multiprobe DES data as [Phys. Rev. Lett. 122, 171301 (2019), 10.1103/PhysRevLett.122.171301] : DES Year 1 (Y1) galaxy clustering and weak lensing, which are sensitive to both growth and geometry, as well as Y1 BAO and Y3 supernovae, which probe geometry. We additionally include external geometric information from BOSS DR12 BAO and a compressed Planck 2015 likelihood, and external growth information from BOSS DR12 RSD. We find no significant disagreement with Ω_m^grow=Ω_m^geo. When DES and external data are analyzed separately, degeneracies with neutrino mass and intrinsic alignments limit our ability to measure Ω_m^grow, but combining DES with external data allows us to constrain both growth and geometric quantities. We also consider a parametrization where we split both Ω_m and w , but find that even our most constraining data combination is unable to separately constrain Ω_m^grow and w^grow. Relative to Λ CDM , splitting growth and geometry weakens bounds on σ₈ but does not alter constraints on h .

ID: 159641
Type: article
Authors: Jimenez-Gallardo, A.; Massaro, F.; Paggi, A.; D'Abrusco, Raffaele; Prieto, M. A.; Peña-Herazo, H. A.; Berta, V.; Ricci, F.; Stuardi, C.; Wilkes, Belinda J.; O'Dea, C. P.; Baum, S. A.; Kraft, Ralph P.; Forman, William R.; Jones-Forman, Christine; Mingo, B.; Liuzzo, E.; Balmaverde, B.; Capetti, A.; Missaglia, V.; Hardcastle, M. J.; Baldi, R. D.; Morabito, L. K.
Abstract: We present a systematic analysis of the extended X-ray emission discovered around 35 FR II radio galaxies from the revised Third Cambridge Catalog (3CR) Chandra Snapshot Survey with redshifts between 0.05 and 0.9. We aimed to (i) test for the presence of extended X-ray emission around FR II radio galaxies, (ii) investigate whether the extended emission origin is due to inverse Compton (IC) scattering of seed photons arising from the cosmic microwave background (CMB) or thermal emission from an intracluster medium (ICM), and (iii) test the impact of this extended emission on hot-spot detection. We investigated the nature of the extended X-ray emission by studying its morphology and compared our results with low-frequency radio observations (i.e., ∼150 MHz) in the TGSS and LOFAR archives, as well as with optical images from Pan-STARRS. In addition, we optimized a search for X-ray counterparts of hot spots in 3CR FR II radio galaxies. We found statistically significant extended emission (>3σ confidence level) along the radio axis of ∼90% and in the perpendicular direction of ∼60% of the galaxies in our sample. We confirmed the detection of seven hot spots in the 0.5-3 keV energy range. In the cases where the emission in the direction perpendicular to the radio axis is comparable to that along the radio axis, we suggest that the underlying radiative process is thermal emission from the ICM. Otherwise, the dominant radiative process is likely nonthermal IC/CMB emission from lobes. We found that nonthermal IC/CMB is the dominant process in ∼70% of the sources in our sample, while thermal emission from the ICM dominates in ∼15% of them.

ID: 159642
Type: article
Authors: Burkhardt, Andrew M.; Loomis, Ryan A.; Shingledecker, Christopher N.; Lee, Kin Long Kelvin; Remijan, Anthony J.; McCarthy, Michael C.; McGuire, Brett A.
Abstract: Benzonitrile (c-C₆H₅CN, where `c' indicates a cyclic structure), a polar proxy for benzene (c-C₆H₆), has the potential to serve as a highly convenient radio probe for aromatic chemistry, provided that this ring can be found in other astronomical sources beyond the molecule-rich prestellar cloud TMC-1. Here we present radio astronomical evidence of benzonitrile in four other prestellar, and possibly protostellar, sources: Serpens 1A, Serpens 1B, Serpens 2 and MC27/L1521F. These detections establish that benzonitrile is not unique to TMC-1; rather, aromatic chemistry appears to be widespread throughout the earliest stages of star formation, probably persisting at least until the initial formation of a protostar. The abundance of benzonitrile far exceeds predictions from models that well reproduce the abundances of carbon chains such as HC₇N, a cyanpolyyne with the same heavy atoms, indicating that the chemistry responsible for planar carbon structures (as opposed to linear ones) in primordial sources is favourable but not well understood. The abundance of benzonitrile relative to carbon chain molecules displays sizable variations between sources within the Taurus and Serpens clouds, implying the importance of physical conditions and initial elemental reservoirs of the clouds themselves.

ID: 159643
Type: article
Authors: Elvis, Martin; Krolikowski, Alanna; Milligan, Tony
Abstract: Numerous missions planned for the next decade are likely to target a handful of small sites of interest on the Moon's surface, creating risks of crowding and interference at these locations. The Moon presents finite and scarce areas with rare topography or concentrations of resources of special value. Locations of interest to science, notably for astronomy, include the Peaks of Eternal Light, the coldest of the cold traps and smooth areas on the far side. Regions richest in physical resources could also be uniquely suited to settlement and commerce. Such sites of interest are both few and small. Typically, there are fewer than ten key sites of each type, each site spanning a few kilometres across. We survey the implications for different kinds of mission and find that the diverse actors pursuing incompatible ends at these sites could soon crowd and interfere with each other, leaving almost all actors worse off. Without proactive measures to prevent these outcomes, lunar actors are likely to experience significant losses of opportunity. We highlight the legal, policy and ethical ramifications. Insights from research on comparable sites on Earth present a path toward managing lunar crowding and interference grounded in ethical and practical near-term considerations.
This article is part of a discussion meeting issue `Astronomy from the Moon: the next decades'.

ID: 159644
Type: article
Authors: Tanoglidis, D.; Drlica-Wagner, A.; Wei, K.; Li, T. S.; Sánchez, J.; Zhang, Y.; Peter, A. H. G.; Feldmeier-Krause, A.; Prat, J.; Casey, K.; Palmese, A.; Sánchez, C.; DeRose, J.; Conselice, C.; Gagnon, L.; Abbott, T. M. C.; Aguena, M.; Allam, S.; Avila, S.; Bechtol, K.; Bertin, E.; Bhargava, S.; Brooks, D.; Burke, D. L.; Rosell, A. Carnero; Kind, M. Carrasco; Carretero, J.; Chang, C.; Costanzi, M.; da Costa, L. N.; De Vicente, J.; Desai, S.; Diehl, H. T.; Doel, P.; Eifler, T. F.; Everett, S.; Evrard, A. E.; Flaugher, B.; Frieman, J.; García-Bellido, J.; Gerdes, D. W.; Gruendl, R. A.; Gschwend, J.; Gutierrez, G.; Hartley, W. G.; Hollowood, D. L.; Huterer, D.; James, David J.; Krause, E.; Kuehn, K.; Kuropatkin, N.; Maia, M. A. G.; March, M.; Marshall, J. L.; Menanteau, F.; Miquel, R.; Ogando, R. L. C.; Paz-Chinchón, F.; Romer, A. K.; Roodman, A.; Sanchez, E.; Scarpine, V.; Serrano, S.; Sevilla-Noarbe, I.; Smith, M.; Suchyta, E.; Tarle, G.; Thomas, D.; Tucker, D. L.; Walker, A. R.; DES Collaboration
Abstract: We present a catalog of 23,790 extended low-surface-brightness galaxies (LSBGs) identified in $\sim 5000\,{\deg }^{2}$ from the first three years of imaging data from the Dark Energy Survey (DES). Based on a single-component Sérsic model fit, we define extended LSBGs as galaxies with g-band effective radii ${R}_{\mathrm{eff}}(g)> 2\buildrel{\prime\prime}\over{.} 5$ and mean surface brightness ${\bar{\mu }}_{\mathrm{eff}}(g)> 24.2\,\mathrm{mag}\,{\mathrm{arcsec}}^{-2}$ . We find that the distribution of LSBGs is strongly bimodal in (g - r) versus (g - i) color space. We divide our sample into red (g - i ≥ 0.60) and blue (g - i 1.5\,\mathrm{kpc}$ and central surface brightness ${\mu }_{0}(g)> 24.0\,\mathrm{mag}\,{\mathrm{arcsec}}^{-2}$ . The wide-area sample of LSBGs in DES can be used to test the role of environment on models of LSBG formation and evolution.

ID: 159645
Type: article
Authors: Leisawitz, David; Amatucci, Edward; Allen, Lynn; Arenberg, Jonathan; Armus, Lee; Battersby, Cara; Bauer, James; Bell, Ray; Benford, Dominic; Bergin, Edward; Booth, Jeffrey T.; Bradford, Charles M.; Bradley, Damon; Carey, Sean; Carter, Ruth; Cooray, Asantha; Corsetti, James; Dewell, Larry; DiPirro, Michael; Drake, Bret G.; East, Matthew; Ennico, Kimberly; Feller, Greg; Flores, Angel; Fortney, Jonathan; Granger, Zachary; Greene, Thomas P.; Howard, Joseph; Kataria, Tiffany; Knight, John S.; Lawrence, Charles; Lightsey, Paul; Mather, John C.; Meixner, Margaret; Melnick, Gary; McMurtry, Craig; Milam, Stefanie; Moseley, Samuel H.; Narayanan, Desika; Nordt, Alison; Padgett, Deborah; Pontoppidan, Klaus; Pope, Alexandra; Rafanelli, Gerard; Redding, David C.; Rieke, George; Roellig, Thomas; Sakon, Itsuki; Sandin, Carly; Sandstrom, Karin; Sengupta, Anita; Sheth, Kartik; Sokolsky, Lawrence M.; Staguhn, Johannes; Steeves, John; Stevenson, Kevin; Su, Kate; Vieira, Joaquin; Webster, Cassandra; Wiedner, Martina; Wright, Edward L.; Wu, Chi; Yanatsis, David; Zmuidzinas, Jonas; Origins Space Telescope Mission Concept and Study Team
Abstract: The Origins Space Telescope will trace the history of our origins from the time dust and heavy elements permanently altered the cosmic landscape to present-day life. How did galaxies evolve from the earliest galactic systems to those found in the universe today? How do habitable planets form? How common are life-bearing worlds? We describe how Origins was designed to answer these alluring questions. We discuss the key decisions taken by the Origins mission concept study team, the rationale for those choices, and how they led through an exploratory design process to the Origins baseline mission concept. To understand the concept solution space, we studied two distinct mission concepts and descoped the second concept, aiming to maximize science per dollar and hit a self-imposed cost target. We report on the study approach and describe the concept evolution. The resulting baseline design includes a 5.9-m diameter telescope cryocooled to 4.5 K and equipped with three scientific instruments. The chosen architecture is similar to that of the Spitzer Space Telescope and requires very few deployments after launch. The cryo-thermal system design leverages James Webb Space Telescope technology and experience.

ID: 159646
Type: article
Authors: Leisawitz, David; Amatucci, Edward; Allen, Lynn; Arenberg, Jonathan; Armus, Lee; Battersby, Cara; Bauer, James; Beaman, Bobby G.; Bell, Ray; Beltran, Porfirio; Benford, Dominic; Bergin, Edward; Bolognese, Jeffrey; Bradford, Charles M.; Bradley, Damon; Burgarella, Denis; Carey, Sean; Chi, J. D. (Danny); Cooray, Asantha; Corsetti, James; D'Asto, Thomas; De Beck, Elvire; Denis, Kevin; Derkacz, Christopher; Dewell, Larry; DiPirro, Michael; Earle, Cleland P.; East, Matthew; Edgington, Samantha; Ennico, Kimberly; Fantano, Louis; Feller, Greg; Folta, David; Fortney, Jonathan; Gavares, Benjamin J.; Generie, Joseph; Gerin, Maryvonne; Granger, Zachary; Greene, Thomas P.; Griffiths, Alex; Harpole, George; Harvey, Keith; Helmich, Frank; Hilliard, Lawrence; Howard, Joseph; Jacoby, Michael; Jamil, Anisa; Jamison, Tracee; Kaltenegger, Lisa; Kataria, Tiffany; Knight, John S.; Knollenberg, Perry; Lawrence, Charles; Lightsey, Paul; Lipscy, Sarah; Mamajek, Eric; Martins, Gregory; Mather, John C.; Meixner, Margaret; Melnick, Gary; Milam, Stefanie; Mooney, Ted; Moseley, Samuel H.; Narayanan, Desika; Neff, Susan; Nguyen, Thanh; Nordt, Alison; Olson, Jeffrey; Padgett, Deborah; Petach, Michael; Petro, Susanna; Pohner, John; Pontoppidan, Klaus; Pope, Alexandra; Ramspacker, Daniel; Rao, Alison; Roellig, Thomas; Sakon, Itsuki; Sandin, Carly; Sandstrom, Karin; Scott, Douglas; Seals, Len; Sheth, Kartik; Sokolsky, Lawrence M.; Staguhn, Johannes; Steeves, John; Stevenson, Kevin; Stoneking, Eric; Su, Kate; Tajdaran, Kiarash; Tompkins, Steven; Vieira, Joaquin; Webster, Cassandra; Wiedner, Martina C.; Wright, Edward L.; Wu, Chi; Zmuidzinas, Jonas
Abstract: The Origins Space Telescope will trace the history of our origins from the time dust and heavy elements permanently altered the cosmic landscape to present-day life. How did galaxies evolve from the earliest galactic systems to those found in the Universe today? How do habitable planets form? How common are life-bearing worlds? To answer these alluring questions, Origins will operate at mid- and far-infrared (IR) wavelengths and offer powerful spectroscopic instruments and sensitivity three orders of magnitude better than that of the Herschel Space Observatory, the largest telescope flown in space to date. We describe the baseline concept for Origins recommended to the 2020 US Decadal Survey in Astronomy and Astrophysics. The baseline design includes a 5.9-m diameter telescope cryocooled to 4.5 K and equipped with three scientific instruments. A mid-infrared instrument (Mid-Infrared Spectrometer and Camera Transit spectrometer) will measure the spectra of transiting exoplanets in the 2.8 to 20 μm wavelength range and offer unprecedented spectrophotometric precision, enabling definitive exoplanet biosignature detections. The far-IR imager polarimeter will be able to survey thousands of square degrees with broadband imaging at 50 and 250 μm. The Origins Survey Spectrometer will cover wavelengths from 25 to 588 μm, making wide-area and deep spectroscopic surveys with spectral resolving power R ∼ 300, and pointed observations at R ∼ 40,000 and 300,000 with selectable instrument modes. Origins was designed to minimize complexity. The architecture is similar to that of the Spitzer Space Telescope and requires very few deployments after launch, while the cryothermal system design leverages James Webb Space Telescope technology and experience. A combination of current-state-of-the-art cryocoolers and next-generation detector technology will enable Origins' natural background-limited sensitivity.

ID: 159647
Type: article
Authors: Wiedner, Martina C.; Aalto, Susanne; Amatucci, Edward G.; Baryshev, Andrey; Battersby, Cara; Belitsky, Victor; Bergin, Edwin A.; Borgo, Bruno; Carter, Ruth C.; Caux, Emmanuel; Cooray, Asantha; Corsetti, James A.; De Beck, Elvire; Delorme, Yan; Desmaris, Vincent; Dipirro, Michael J.; Ellison, Brian; Di Giorgio, Anna M.; Eggens, Martin; Gallego, Juan-Daniel; Gerin, Maryvonne; Goldsmith, Paul F.; Goldstein, Christophe; Helmich, Frank; Herpin, Fabrice; Hills, Richard E.; Hogerheijde, Michiel R.; Hunt, Leslie K.; Jellema, Willem; Keizer, Geert; Krieg, Jean-Michel; Kroes, Gabby; Laporte, Philippe; Laurens, André; Leisawitz, David T.; Lis, Dariusz C.; Martins, Gregory E.; Mehdi, Imran; Meixner, Margaret; Melnick, Gary; Milam, Stefanie N.; Neufeld, David A.; Nguyen Tuong, Napoléon; Plume, René; Pontoppidan, Klaus M.; Quertier-Dagorn, Benjamin; Risacher, Christophe; Staguhn, Johannes G.; Tong, Edward; Viti, Serena; Wyrowski, Friedrich
Abstract: The Heterodyne Receiver for Origins (HERO) is the first detailed study of a heterodyne focal plane array receiver for space applications. HERO gives the Origins Space Telescope the capability to observe at very high spectral resolution (R = 10⁷) over an unprecedentedly large far-infrared (FIR) wavelengths range (111 to 617 μm) with high sensitivity, with simultaneous dual polarization and dual-frequency band operation. The design is based on prior successful heterodyne receivers, such as Heterodyne Instrument for the Far-Infrared /Herschel, but surpasses it by one to two orders of magnitude by exploiting the latest technological developments. Innovative components are used to keep the required satellite resources low and thus allowing for the first time a convincing design of a large format heterodyne array receiver for space. HERO on Origins is a unique tool to explore the FIR universe and extends the enormous potential of submillimeter astronomical spectroscopy into new areas of astronomical research.

ID: 159648
Type: article
Authors: Meixner, Margaret; Cooray, Asantha; Leisawitz, David T.; Staguhn, Johannes G.; Armus, Lee; Battersby, Cara; Bauer, James; Benford, Dominic; Bergin, Edwin; Bradford, Charles Matt; Burgarella, Denis; Carey, Sean; De Beck, Elvire; Ennico-Smith, Kimberly; Fortney, Jonathan J.; Gerin, Maryvonne; Helmich, Frank P.; Kataria, Tiffany; Mamajek, Eric E.; Melnick, Gary J.; Milam, Stefanie N.; Moseley, Samuel Harvey; Narayanan, Desika; Neff, Susan G.; Padgett, Deborah; Pontoppidan, Klaus; Pope, Alexandra; Roellig, Thomas L.; Sakon, Itsuki; Sandstrom, Karin; Scott, Douglas; Sheth, Kartik; Stevenson, Kevin B.; Su, Kate Y.; Vieira, Joaquin; Wiedner, Martina C.; Wright, Edward; Zmuidzinas, Jonas; Origins Study Team
Abstract: The Origins Space Telescope (Origins) concept is designed to investigate the creation and dispersal of elements essential to life, the formation of planetary systems, and the transport of water to habitable worlds and the atmospheres of exoplanets around nearby K- and M-dwarfs to identify potentially habitable-and even inhabited-worlds. These science priorities are aligned with NASA's three major astrophysics science goals: How does the Universe work? How did we get here? and Are we alone? We briefly describe the science case that arose from the astronomical community and the science traceability matrix for Origins. The science traceability matrix prescribes the design of Origins and demonstrates that it will address the key science questions motivated by the science case.

ID: 159554
Type: article
Authors: Long, Feng; Bosman, Arthur D.; Cazzoletti, Paolo; van Dishoeck, Ewine F.; Öberg, Karin I.; Facchini, Stefano; Tazzari, Marco; Guzmán, Viviana V.; Testi, Leonardo
Abstract: Context. The distributions and abundances of molecules in protoplanetary disks are powerful tracers of the physical and chemical disk structures. The abundance ratios of HCN and its isomer HNC are known to be sensitive to gas temperature. Their line ratios might therefore offer a unique opportunity to probe the properties of the emitting gas.
Aims: We investigate the HNC and HCN line emission in disks at (sub-)millimeter wavelengths and explore their potential utility for probing disk temperature and other disk properties.
Methods: Using the 2D thermochemical code DALI, we ran a set of disk models accounting for different stellar properties and radial and vertical disk structures, with an updated chemical network for the nitrogen chemistry. These modeling results were then compared with observations, including new observations obtained with the Atacama Large Millimeter/submillimeter Array (ALMA) of HNC J = 3‒2 for the TW Hya disk and HNC J = 1‒0 for 29 disks in Lupus.
Results: Similar to CN, HCN and HNC have brighter line emission in models with larger disk flaring angles and higher UV fluxes. HNC and HCN are predicted to be abundant in the warm surface layer and outer midplane region, which results in ring-shaped emission patterns. However, the precise emitting regions and emission morphology depend on the probed transition, as well as on other parameters such as C and O abundances. The modeled HNC-to-HCN line intensity ratio increases from <0.1 in the inner disk to up to 0.8 in the outer disk regions, which can be explained by efficient HNC destruction at high temperatures. Disk-integrated HNC line fluxes from current scarce observations and its radial distribution in the TW Hya disk are broadly consistent with our model predictions.
Conclusions: The HNC-to-HCN flux ratio robustly increases with radius (decreasing temperature), but its use as a chemical thermometer in disks is affected by other factors, including UV flux and C and O abundances. High-spatial resolution ALMA disk observations of HNC and HCN that can locate the emitting layers would have the great potential to constrain both the disk thermal and UV radiation structures, and also to verify our understanding of the nitrogen chemistry.

ID: 159555
Type: article
Authors: Paggi, A.; Massaro, F.; Peña-Herazo, H. A.; Missaglia, V.; Ricci, F.; Stuardi, C.; Kraft, R. P.; Tremblay, G. R.; Baum, S. A.; Wilkes, B. J.
Abstract: Context. The diffuse X-ray emission surrounding radio galaxies is generally interpreted either as due to inverse Compton scattering of nonthermal radio-emitting electrons on the cosmic microwave background (IC/CMB), or as due to thermal emission arising from the hot gas of the intergalactic medium (IGM) permeating galaxy clusters hosting such galaxies, or as a combination of both. In this work, we present an imaging and spectral analysis of Chandra observations for the radio galaxy 3C 187 to investigate its diffuse X-ray emission and constrain the contribution of these various physical mechanisms.
Aims: The main goals of this work are the following: (i) to evaluate the extension of the diffuse X-ray emission from this source; (ii) to investigate the two main processes, IC/CMB and thermal emission from the IGM, which can account for the origin of this emission; and (iii) to test the possibility that 3C 187 belongs to a cluster of galaxies, which can account for the observed diffuse X-ray emission.
Methods: To evaluate the extension of the X-ray emission around 3C 187, we extracted surface flux profiles along and across the radio axis. We also extracted X-ray spectra in the region of the radio lobes and in the cross-cone region to estimate the contribution of the nonthermal (IC/CMB) and thermal (IGM) processes to the observed emission, making use of radio (VLA and GMRT) data to investigate the multiwavelength emission arising from the lobes. We collected Pan-STARRS photometric data to investigate the presence of a galaxy cluster hosting 3C 187, looking for the presence of a "red sequence" in the source field in the form of a tight clustering of galaxies in the color space. In addition, we made use of observations performed with the COSMOS spectrograph at the Victor Blanco Telescope to estimate the redshift of the sources in the field of 3C 187 to verify if they are gravitationally bound, as we would expect in a cluster of galaxies.
Results: The diffuse X-ray emission around 3C 187 is found to extend in the soft 0.3 - 3 keV band up to ∼850 kpc along the radio lobe direction and ∼530 kpc in the cross-cone direction, and it appears enhanced in correspondence with the radio lobes. Spectral X-ray analysis in the cross-cones indicates a thermal origin for the emission in this region with a temperature ∼4 keV. In the radio lobes, the X-ray spectral analysis in combination with the radio data suggests a dominant IC/CMB radiation in these regions, however we do not rule out a significant thermal contribution. Assuming that the radiation observed in the radio lobes is due to the IGM, the emission from the N and S cones can be interpreted as arising from hot gas with temperatures of ∼3 keV and ∼5 keV, respectively, and found to be in pressure equilibrium with the surrounding gas. Using Pan-STARRS optical data we found that 3C 187 belongs to a red sequence of ∼40 optical sources in the field whose color distribution is significantly different from background sources. We were able to collect optical spectra for only one of these cluster candidates and for 22 field (i.e., noncluster candidates) sources. While the latter show stellar spectra, the former feature a galactic spectrum with a redshift close to 3C 187 nucleus.
Conclusions: The diffuse X-ray emission around 3C 187 is elongated along the radio axis and enhanced in correspondence with the radio lobes. This indicates a morphological connection between the emission in the two energy bands and thus suggests a dominating IC/CMB mechanism in these regions. This scenario is reinforced by multiwavelength radio X-ray emission, which in these regions is compatible with IC/CMB radiation. The X-ray spectral analysis however does not rule out a significant contribution to the observed emission from thermal gas, which would be able to emit over tens of gigayears and in pressure equilibrium with the surroundings. Optical data indicate that 3C 187 may belong to a cluster of galaxies, whose IGM would contribute to the X-ray emission observed around the source. Additional X-ray and optical spectroscopic observations are however needed to secure these results and get a more clear picture of the physical processes at play in 3C 187.

ID: 159556
Type: article
Authors: Garilli, B.; McLure, R.; Pentericci, L.; Franzetti, P.; Gargiulo, A.; Carnall, A.; Cucciati, O.; Iovino, A.; Amorin, R.; Bolzonella, M.; Bongiorno, A.; Castellano, M.; Cimatti, A.; Cirasuolo, M.; Cullen, F.; Dunlop, J.; Elbaz, D.; Finkelstein, S.; Fontana, A.; Fontanot, F.; Fumana, M.; Guaita, L.; Hartley, W.; Jarvis, M.; Juneau, S.; Maccagni, D.; McLeod, D.; Nandra, K.; Pompei, E.; Pozzetti, L.; Scodeggio, M.; Talia, M.; Calabrò, A.; Cresci, G.; Fynbo, J. P. U.; Hathi, N. P.; Hibon, P.; Koekemoer, A. M.; Magliocchetti, M.; Salvato, M.; Vietri, G.; Zamorani, G.; Almaini, O.; Balestra, I.; Bardelli, S.; Begley, R.; Brammer, G.; Bell, E. F.; Bowler, R. A. A.; Brusa, M.; Buitrago, F.; Caputi, C.; Cassata, P.; Charlot, S.; Citro, A.; Cristiani, S.; Curtis-Lake, E.; Dickinson, M.; Fazio, Giovanni; Ferguson, H. C.; Fiore, F.; Franco, M.; Georgakakis, A.; Giavalisco, M.; Grazian, A.; Hamadouche, M.; Jung, I.; Kim, S.; Khusanova, Y.; Le Fèvre, O.; Longhetti, M.; Lotz, J.; Mannucci, F.; Maltby, D.; Matsuoka, K.; Mendez-Hernandez, H.; Mendez-Abreu, J.; Mignoli, M.; Moresco, M.; Nonino, M.; Pannella, M.; Papovich, C.; Popesso, P.; Roberts-Borsani, G.; Rosario, D. J.; Saldana-Lopez, A.; Santini, P.; Saxena, A.; Schaerer, D.; Schreiber, C.; Stark, D.; Tasca, L. A. M.; Thomas, R.; Vanzella, E.; Wild, V.; Williams, C.; Zucca, E.
Abstract: VANDELS is an ESO Public Spectroscopic Survey designed to build a sample of high-signal-to-noise ratio, medium-resolution spectra of galaxies at redshifts between 1 and 6.5. Here we present the final Public Data Release of the VANDELS Survey, comprising 2087 redshift measurements. We provide a detailed description of sample selection, observations, and data reduction procedures. The final catalogue reaches a target selection completeness of 40% at i_AB = 25. The high signal-to-noise ratio of the spectra (above 7 in 80% of the spectra) and the dispersion of 2.5 Å allowed us to measure redshifts with high precision, the redshift measurement success rate reaching almost 100%. Together with the redshift catalogue and the reduced spectra, we also provide optical mid-infrared photometry and physical parameters derived through fitting the spectral energy distribution. The observed galaxy sample comprises both passive and star forming galaxies covering a stellar mass range of 8.3 = 25. The high signal-to-noise ratio of the spectra (above 7 in 80% of the spectra) and the dispersion of 2.5 Å allowed us to measure redshifts with high precision, the redshift measurement success rate reaching almost 100%. Together with the redshift catalogue and the reduced spectra, we also provide optical mid-infrared photometry and physical parameters derived through fitting the spectral energy distribution. The observed galaxy sample comprises both passive and star forming galaxies covering a stellar mass range of 8.3 _*/M_⊙) < 11.7.
This paper, which presents the final data release of the final high-redshift VIMOS survey, is dedicated to the memory of Olivier Le Fèvre, PI of the VIMOS instrument, world renowned expert of extragalactic spectroscopy and a pioneer in spectroscopy of the distant Universe.
All catalogues and spectra are accessible through the survey database (http://vandels.inaf.it) where all information can be queried interactively, and via the ESO Archive (https://www.eso.org/qi/).

ID: 159557
Type: article
Authors: Bulut, N.; Roncero, O.; Aguado, A.; Loison, J. -C; Navarro-Almaida, D.; Wakelam, V.; Fuente, A.; Roueff, E.; Le Gal, Romane; Caselli, P.; Gerin, M.; Hickson, K. M.; Spezzano, S.; Riviére-Marichalar, P.; Alonso-Albi, T.; Bachiller, R.; Jiménez-Serra, I.; Kramer, C.; Tercero, B.; Rodriguez-Baras, M.; García-Burillo, S.; Goicoechea, J. R.; Treviño-Morales, S. P.; Esplugues, G.; Cazaux, S.; Commercon, B.; Laas, J.; Kirk, J.; Lattanzi, V.; Martín-Doménech, Rafael; Muñoz-Caro, G.; Pineda, J.; Ward-Thompson, D.; Tafalla, M.; Marcelino, N.; Malinen, J.; Friesen, R.; Giuliano, B. M.; Agúndez, M.; Hacar, A.
Abstract: Context. Carbon monosulphide (CS) is among the most abundant gas-phase S-bearing molecules in cold dark molecular clouds. It is easily observable with several transitions in the millimeter wavelength range, and has been widely used as a tracer of the gas density in the interstellar medium in our Galaxy and external galaxies. However, chemical models fail to account for the observed CS abundances when assuming the cosmic value for the elemental abundance of sulfur.
Aims: The CS+O → CO + S reaction has been proposed as a relevant CS destruction mechanism at low temperatures, and could explain the discrepancy between models and observations. Its reaction rate has been experimentally measured at temperatures of 150-400 K, but the extrapolation to lower temperatures is doubtful. Our goal is to calculate the CS+O reaction rate at temperatures <150 K which are prevailing in the interstellar medium.
Methods: We performed ab initio calculations to obtain the three lowest potential energy surfaces (PES) of the CS+O system. These PESs are used to study the reaction dynamics, using several methods (classical, quantum, and semiclassical) to eventually calculate the CS + O thermal reaction rates. In order to check the accuracy of our calculations, we compare the results of our theoretical calculations for T ~ 150-400 K with those obtained in the laboratory.
Results: Our detailed theoretical study on the CS+O reaction, which is in agreement with the experimental data obtained at 150-400 K, demonstrates the reliability of our approach. After a careful analysis at lower temperatures, we find that the rate constant at 10 K is negligible, below 10^-15 cm³ s^-1, which is consistent with the extrapolation of experimental data using the Arrhenius expression.
Conclusions: We use the updated chemical network to model the sulfur chemistry in Taurus Molecular Cloud 1 (TMC 1) based on molecular abundances determined from Gas phase Elemental abundances in Molecular CloudS (GEMS) project observations. In our model, we take into account the expected decrease of the cosmic ray ionization rate, ζ_H2, along the cloud. The abundance of CS is still overestimated when assuming the cosmic value for the sulfur abundance.

ID: 159558
Type: article
Authors: Kamiński, Tomasz; Steffen, W.; Bujarrabal, V.; Tylenda, R.; Menten, K. M.; Hajduk, M.
Abstract: CK Vul is the remnant of an energetic eruption known as Nova 1670 that is thought to be caused by a stellar merger. The remnant is composed of (1) a large hourglass nebula of recombining gas (of 71'' in size), very similar to some classical planetary and pre-planetary nebulae (PPNe), and (2) a much smaller and cooler inner remnant that is prominent in millimeter-wave emission from molecules. We investigate the three-dimensional spatio-kinematic structure of both components. Our analysis of the hourglass structure yields a revised distance to the object of >2.6 kpc, at least 3.7 times greater than previously assumed. At this distance, the stellar remnant has a bolometric luminosity >12 L_⊙ and is surrounded by molecular material with a total mass >0.8 M_⊙ (the latter value has a large systematic uncertainty). We also analyzed the architecture of the inner molecular nebula using ALMA observations of rotational emission lines obtained at subarcsecond resolution. We find that the distribution of neutral and ionized gas in the lobes can be reproduced by several nested and incomplete shells or jets with different velocity fields and varying orientations. The analysis indicates that the molecular remnant was created in several ejection episodes, possibly involving an interacting binary system. We calculated the linear momentum (≈10⁴⁰ g cm s^-1) and kinetic energy (≈10⁴⁷ erg) of the CK Vul outflows and find values that are within the limits typical for classical PPNe. Given the similarities of the CK Vul outflows to PPNe, we suggest there may be CK Vul analogs among wrongly classified PPNe with low intrinsic luminosities, especially among PPNe with post-red-giant-branch central stars.
Two movies associated to Fig. 4 are available at http://www.aanda.org

ID: 159559
Type: article
Authors: Rajpurohit, K.; Wittor, D.; van Weeren, R. J.; Vazza, F.; Hoeft, M.; Rudnick, L.; Locatelli, N.; Eilek, J.; Forman, W. R.; Bonafede, A.; Bonnassieux, E.; Riseley, C. J.; Brienza, M.; Brunetti, G.; Brüggen, M.; Loi, F.; Rajpurohit, A. S.; Röttgering, H. J. A.; Botteon, A.; Clarke, T. E.; Drabent, A.; Domínguez-Fernández, P.; Di Gennaro, G.; Gastaldello, F.
Abstract: Radio relics are diffuse, extended synchrotron sources that originate from shock fronts generated during cluster mergers. The massive merging galaxy cluster MACS J0717.5+3745 hosts one of the more complex relics known to date. We present upgraded Giant Metrewave Radio Telescope band 3 (300-500 MHz) and band 4 (550-850 MHz) observations. These new observations, combined with published VLA and the new LOFAR HBA data, allow us to carry out a detailed, high spatial resolution spectral analysis of the relic over a broad range of frequencies. The integrated spectrum of the relic closely follows a power law between 144 MHz and 5.5 GHz with a mean spectral slope α = -1.16 ± 0.03. Despite the complex morphology of this relic, its subregions and the other isolated filaments also follow power-law behaviors, and show similar spectral slopes. Assuming diffusive shock acceleration, we estimated a dominant Mach number of ∼3.7 for the shocks that make up the relic. A comparison with recent numerical simulations suggests that in the case of radio relics, the slopes of the integrated radio spectra are determined by the Mach number of the accelerating shock, with α nearly constant, namely between -1.13 and -1.17, for Mach numbers 3.5 - 4.0. The spectral shapes inferred from spatially resolved regions show curvature, we speculate that the relic is inclined along the line of sight. The locus of points in the simulated color-color plots changes significantly with the relic viewing angle. We conclude that projection effects and inhomogeneities in the shock Mach number dominate the observed spectral properties of the relic in this complex system. Based on the new observations we raise the possibility that the relic and a narrow-angle-tailed radio galaxy are two different structures projected along the same line of sight.

ID: 159560
Type: article
Authors: Ghizzardi, Simona; Molendi, Silvano; van der Burg, Remco; De Grandi, Sabrina; Bartalucci, Iacopo; Gastaldello, Fabio; Rossetti, Mariachiara; Biffi, Veronica; Borgani, Stefano; Eckert, Dominique; Ettori, Stefano; Gaspari, Massimo; Ghirardini, Vittorio; Rasia, Elena
Abstract: We present the first metal abundance profiles for a representative sample of massive clusters. Our measurements extend to R₅₀₀ and are corrected for a systematic error plaguing previous outskirt estimates. Our profiles flatten out at large radii, admittedly not a new result, however the radial range and representative nature of our sample extends its import well beyond previous findings. We find no evidence of segregation between cool-core and non-cool-core systems beyond ∼0.3 R₅₀₀, implying that, as was found for thermodynamic properties, the physical state of the core does not affect global cluster properties. Our mean abundance within R₅₀₀ shows a very modest scatter, shows a very modest scatter, ₅₀₀, can be reduced.

ID: 159561
Type: article
Authors: Luminari, A.; Nicastro, Fabrizio; Elvis, Martin; Piconcelli, E.; Tombesi, F.; Zappacosta, Luca; Fiore, F.
Abstract: Context. Ultra-fast outflows (UFOs) have become an established feature in analyses of the X-ray spectra of active galactic nuclei (AGN). According to the standard picture, they are launched at accretion disc scales with relativistic velocities, up to 0.3-0.4 times the speed of light. Their high kinetic power is enough to induce an efficient feedback on a galactic scale, possibly contributing to the co-evolution between the central supermassive black hole (SMBH) and the host galaxy. It is, therefore, of paramount importance to gain a full understanding of UFO physics and, in particular, of the forces driving their acceleration and the relation to the accretion flow from which they originate.
Aims: In this paper, we investigate the impact of special relativity effects on the radiative pressure exerted onto the outflow. The radiation received by the wind decreases for increasing outflow velocity, v, implying that the standard Eddington limit argument has to be corrected according to v. Due to the limited ability of the radiation to counteract the black hole gravitational attraction, we expect to find lower typical velocities with respect to the non-relativistic scenario.
Methods: We integrated the relativistic-corrected outflow equation of motion for a realistic set of starting conditions. We concentrated on a range of ionisations, column densities, and launching radii consistent with those typically estimated for UFOs. We explore a one-dimensional, spherical geometry and a three-dimensional setting with a rotating, thin accretion disc.
Results: We find that the inclusion of special relativity effects leads to sizeable differences in the wind dynamics and that v is reduced up to 50% with respect to the non-relativistic treatment. We compare our results with a sample of UFOs from the literature and we find that the relativistic-corrected velocities are systematically lower than the reported ones, indicating the need for an additional mechanism, such as magnetic driving, to explain the highest velocity components. Finally, we note that these conclusions, derived for AGN winds, are generally applicable.

ID: 159562
Type: article
Authors: Rajpurohit, K.; Brunetti, G.; Bonafede, A.; van Weeren, R. J.; Botteon, A.; Vazza, F.; Hoeft, M.; Riseley, C. J.; Bonnassieux, E.; Brienza, M.; Forman, W. R.; Röttgering, H. J. A.; Rajpurohit, A. S.; Locatelli, N.; Shimwell, T. W.; Cassano, R.; Di Gennaro, G.; Brüggen, M.; Wittor, D.; Drabent, A.; Ignesti, A.
Abstract: We present new LOw-Frequency ARray observations of the massive merging galaxy cluster MACS J0717.5+3745, located at a redshift of 0.5458. The cluster hosts the most powerful radio halo known to date. These new observations, in combination with published uGMRT (300-850 MHz) and VLA (1-6.5 GHz) data, reveal that the halo is more extended than previously thought, with a largest linear size of ∼2.2 Mpc, making it one of the largest known halos. The halo shows a steep spectrum (α_{144 MHz}^{1.5 GHz} ∼ -1.4) and a steepening (α_{1.5 GHz}^{5.5 GHz} ∼ -1.9) above 1.5 GHz. We find a strong scattering in spectral index maps on scales of 50-100 kpc. We suggest that such a strong scattering may be a consequence of the regime where inverse Compton dominates the energy losses of electrons. The spectral index becomes steeper and shows an increased curvature in the outermost regions of the halo. We combined the radio data with Chandra observations to investigate the connection between the thermal and nonthermal components of the intracluster medium (ICM). Despite a significant substructure in the halo emission, the radio brightness correlates strongly with the X-ray brightness at all observed frequencies. The radio-versus-X-ray brightness correlation slope steepens at a higher radio frequency (from b_{144 MHz} = 0.67 ± 0.05 to b_{3.0 GHz} = 0.98 ± 0.09) and the spectral index shows a significant anticorrelation with the X-ray brightness. Both pieces of evidence further support a spectral steepening in the external regions. The compelling evidence for a steep spectral index, the existence of a spectral break above 1.5 GHz, and the dependence of radio and X-ray surface brightness correlation on frequency are interpreted in the context of turbulent reacceleration models. Under this scenario, our results allowed us to constrain that the turbulent kinetic pressure of the ICM is up to 10%.

ID: 159563
Type: article
Authors: Pizzardo, M.; Di Gioia, S.; Diaferio, A.; De Boni, C.; Serra, A. L.; Geller, Margaret J.; Sohn, Jubee; Rines, K.; Baldi, M.
Abstract: We use a new spherical accretion recipe tested on N-body simulations to measure the observed mass accretion rate (MAR) of 129 clusters in the Cluster Infall Regions in the Sloan Digital Sky Survey (CIRS) and in the Hectospec Cluster Survey (HeCS). The observed clusters cover the redshift range of 0.01 ¹⁴ - 10¹⁵ h^-1 M_⊙. Based on three-dimensional mass profiles of simulated clusters reaching beyond the virial radius, our recipe returns MARs that agree with MARs based on merger trees. We adopt this recipe to estimate the MAR of real clusters based on measurements of the mass profile out to ∼3R₂₀₀. We use the caustic method to measure the mass profiles to these large radii. We demonstrate the validity of our estimates by applying the same approach to a set of mock redshift surveys of a sample of 2000 simulated clusters with a median mass of M₂₀₀ = 10¹⁴ h^-1 M_⊙ as well as a sample of 50 simulated clusters with a median mass of M₂₀₀ = 10¹⁵ h^-1 M_⊙: the median MARs based on the caustic mass profiles of the simulated clusters are unbiased and agree within 19% with the median MARs based on the real mass profile of the clusters. The MAR of the CIRS and HeCS clusters increases with the mass and the redshift of the accreting cluster, which is in excellent agreement with the growth of clusters in the ΛCDM model.

ID: 159564
Type: article
Authors: Vincent, F. H.; Wielgus, Maciek; Abramowicz, M. A.; Gourgoulhon, E.; Lasota, J. -P; Paumard, T.; Perrin, G.
Abstract: Context. The Event Horizon Telescope (EHT) collaboration recently obtained the first images of the surroundings of the supermassive compact object M87* at the center of the galaxy M87. This provides a fascinating probe of the properties of matter and radiation in strong gravitational fields. It is important to determine from the analysis of these results what can and cannot be inferred about the nature of spacetime around M87*
Aims: We want to develop a simple analytic disk model for the accretion flow of M87*. Compared to general-relativistic magnetohydrodynamic models, this new approach has the advantage that it is independent of the turbulent character of the flow and is controlled by only a few easy-to-interpret, physically meaningful parameters. We want to use this model to predict the image of M87*, assuming that it is either a Kerr black hole or an alternative compact object.
Methods: We computed the synchrotron emission from the disk model and propagate the resulting light rays to the far-away observer by means of relativistic ray tracing. Such computations were performed assuming different spacetimes, such as Kerr, Minkowski, nonrotating ultracompact star, rotating boson star, or Lamy spinning wormhole. We performed numerical fits of these models to the EHT data.
Results: We discuss the highly lensed features of Kerr images and show that they are intrinsically linked to the accretion-flow properties and not only to gravitation. This fact is illustrated by the notion of the secondary ring, which we introduce. Our model of a spinning Kerr black hole predicts mass and orientation consistent with the EHT interpretation. The non-Kerr images result in a similar quality of numerical fits and may appear very similar to Kerr images, once blurred to the EHT resolution. This implies that a strong test of the Kerr spacetime may be out of reach with the current data. We note that future developments of the EHT could alter this situation.
Conclusions: Our results show the importance of studying alternatives to the Kerr spacetime to be able to test the Kerr paradigm unambiguously. More sophisticated treatments of non-Kerr spacetimes and more advanced observations are needed to proceed further in this direction.

ID: 159565
Type: article
Authors: Garufi, A.; Podio, L.; Codella, C.; Fedele, D.; Bianchi, E.; Favre, C.; Bacciotti, F.; Ceccarelli, C.; Mercimek, S.; Rygl, K.; Teague, Richard; Testi, L.
Abstract: We present an overview of the ALMA chemical survey of disk-outflow sources in Taurus (ALMA-DOT), a campaign devoted to the characterization of the molecular emission from partly embedded young stars. The project is aimed at attaining a better understanding of the gaseous products delivered to planets by means of high-resolution maps of the assorted lines probing disks at the time of planet formation (≲1 Myr). Nine different molecules are surveyed through our observations of six Class I/flat-spectrum sources. As part of a series of articles analyzing specific targets and molecules, in this work we describe the sample and provide a general overview of the results, focusing specifically on the spatial distribution, column densities, and abundance ratios of H₂CO, CS, and CN. In these embedded sources, the ¹²CO emission is dominated by envelope and outflow emission while the CS and, especially, the H₂CO are good tracers of the gaseous disk structure. The spatial distribution and brightness of the o-H₂CO 3_1,2-2_1,1 and CS 5-4 lines are very similar to each other and across all targets. The CN 2-1 line emission is fainter and distributed over radii larger than the dust continuum. The H₂CO and CS emission is always dimmed in the inner ~50 au. While the suppression by the dusty disk and absorption by the line-of-sight material significantly contributes to this inner depression, an actual decrease in the column density is plausible in most cases, making the observed ring-like morphology realistic. We also found that the gaseous disk extent, when traced by H₂CO (150-390 au), is always 60% larger than the dust disk. This systematic discrepancy may, in principle, be explained by the different optical depth of continuum and line emission without invoking any dust radial drift. Finally, the o-H₂CS 7_1,6-6_1,5 and CH₃OH 5_0,5-4_0,4 line emission are detected in two disks and one disk, respectively, while the HDO is never detected. The H₂CO column densities are 12-50 times larger than those inferred for Class II sources while they are in line with those of other Class 0/I. The CS column densities are lower than those of H₂CO, which is an opposite trend with regard to Class II objects. We also inferred abundance ratios between the various molecular species finding, among others, a H₂CS/H₂CO ratio that is systematically lower than unity (0.4-0.7 in HL Tau, 0.1 - 0.2 in IRAS 04302+2247, and CO ratio that is systematically lower than unity (0.4-0.7 in HL Tau, 0.1 - 0.2 in IRAS 04302+2247, and ₃OH/H₂CO ratio (<0.7 in HL Tau and 0.5-0.7 in IRAS 04302+2247) that is lower than the only available estimate in a protoplanetary disks (1.3 in TW Hya) and between one and two orders of magnitude lower than those of the hot corinos around Class 0 protostars. These results are a first step toward the characterization of the disk's chemical evolution, which ought to be complemented by subsequent observations of less exceptional disks and customized thermo-chemical modeling.

ID: 159566
Type: article
Authors: Kurtovic, N. T.; Pinilla, P.; Long, Feng; Benisty, M.; Manara, C. F.; Natta, A.; Pascucci, I.; Ricci, L.; Scholz, A.; Testi, L.
Abstract: Context. The discovery of giant planets orbiting very low mass stars (VLMS) and the recent observed substructures in disks around VLMS is challenging planet formation models. Specifically, radial drift of dust particles is a catastrophic barrier in these disks, which prevents the formation of planetesimals and therefore planets.
Aims: We aim to estimate if structures, such as cavities, rings, and gaps, are common in disks around VLMS and to test models of structure formation in these disks. We also aim to compare the radial extent of the gas and dust emission in disks around VLMS, which can give us insight about radial drift.
Methods: We studied six disks around VLMS in the Taurus star-forming region using ALMA Band 7 (~340 GHz) at a resolution of ~0.1″. The targets were selected because of their high disk dust content in their stellar mass regime.
Results: Our observations resolve the disk dust continuum in all disks. In addition, we detect the ¹²CO (J = 3-2) emission line in all targets and ¹³CO (J = 3-2) in five of the six sources. The angular resolution allows the detection of dust substructures in three out of the six disks, which we studied by using UV-modeling. Central cavities are observed in the disks around stars MHO 6 (M 5.0) and CIDA 1 (M 4.5), while we have a tentative detection of a multi-ringed disk around J0433. We estimate that a planet mass of ~0.1 M_Jup or ~0.4 M_Saturn is required for a single planet to create the first gap in J0433. For the cavities of MHO 6 and CIDA 1, a Saturn-mass planet (~0.3 M_Jup) is required. The other three disks with no observed structures are the most compact and faintest in our sample, with the radius enclosing 90% of the continuum emission varying between ~13 and 21 au. The emission of ¹²CO and ¹³CO is more extended than the dust continuum emission in all disks of our sample. When using the ¹²CO emission to determine the gas disk extension R_gas, the ratio of R_gas/R_dust in our sample varies from 2.3 to 6.0. One of the disks in our sample, CIDA 7, has the largest R_gas/R_dust ratio observed so far, which is consistent with models of radial drift being very efficient around VLMS in the absence of substructures.
Conclusions: Given our limited angular resolution, substructures were only directly detected in the most extended disks, which represent 50% of our sample, and there are hints of unresolved structured emission in one of the bright smooth sources. Our observations do not exclude giant planet formation on the substructures observed. A comparison of the size and luminosity of VLMS disks with their counterparts around higher mass stars shows that they follow a similar relation.
The reduced images and datacubes are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/cat/J/A+A/645/A139

ID: 159524
Type: article
Authors: Bose, Sownak; Loeb, Abraham
Abstract: We use the IllustrisTNG (TNG) simulations of galaxy formation to measure the velocity dispersion profiles of dark matter and stars in Milky Way-mass, galaxy group, and cluster-scale dark matter halos. The mean profiles calculated from both tracers are similar in shape, exhibiting a large halo-to-halo scatter around the average profile. The so-called "splashback" radius demarcates the outer boundary of the halo, and manifests as a kink in the velocity dispersion profile, located on average between similar to 1.0-1.5r (200m ), where r (200m ) is the radius within which the density of the halo equals 200 times the background density of the universe. We find that this location may also be identified as the radius at which the (stacked) dispersion profile drops to 60% of its peak value (for line-of-sight motions in TNG halos). We further show that the scatter in the dispersion profiles may be attributed to the variations in the assembly history of the host halos. In particular, this segregates the profile into two regimes: one within similar to 0.1r (200m ), where the scatter is set by the early assembly history of the halo; and the other beyond this radius, where the scatter is influenced more strongly by its late-time assembly. Finally, we show that a two-parameter model can be used to fit the measured velocity dispersion profiles and the fit parameters can be related directly to two fundamental halo properties: mass and concentration. We describe a simple model that allows us to express the stellar velocity dispersion profile in terms of these halo properties only.

ID: 159525
Type: article
Authors: Hinkley, Sasha; Matthews, Elisabeth C.; Lefevre, Charlene; Lestrade, Jean-Francois; Kennedy, Grant; Mawet, Dimitri; Stapelfeldt, Karl R.; Ray, Shrishmoy; Mamajek, Eric; Bowler, Brendan P.; Wilner, David; Williams, Jonathan; Ansdell, Megan; Wyatt, Mark; Lau, Alexis; Phillips, Mark W.; Fernandez, Jorge; Gagne, Jonathan; Bubb, Emma; Sutlieff, Ben J.; Wilson, Thomas J. G.; Matthews, Brenda; Ngo, Henry; Piskorz, Danielle; Crepp, Justin R.; Gonzalez, Erica; Mann, Andrew W.; Mace, Gregory
Abstract: We report the discovery of a circumstellar debris disk viewed nearly edge-on and associated with the young, K1 star BD+45 degrees 598 using high-contrast imaging at 2.2 mu m obtained at the W.M. Keck Observatory. We detect the disk in scattered light with a peak significance of similar to 5 sigma over three epochs, and our best-fit model of the disk is an almost edge-on similar to 70 au ring, with inclination angle similar to 87 degrees. Using the NOEMA interferometer at the Plateau de Bure Observatory operating at 1.3 mm, we find resolved continuum emission aligned with the ring structure seen in the 2.2 mu m images. We estimate a fractional infrared luminosity of L-IR/L-tot similar or equal to 6(-1)(+2) x 10(-4), higher than that of the debris disk around AU Mic. Several characteristics of BD+45 degrees 598, such as its galactic space motion, placement in a color-magnitude diagram, and strong presence of lithium, are all consistent with its membership in the beta Pictoris Moving Group with an age of 23 +/- 3 Myr. However, the galactic position for BD+45 degrees 598 is slightly discrepant from previously known members of the beta Pictoris Moving Group, possibly indicating an extension of members of this moving group to distances of at least 70 pc. BD+45 degrees 598 appears to be an example from a population of young circumstellar debris systems associated with newly identified members of young moving groups that can be imaged in scattered light, key objects for mapping out the early evolution of planetary systems from similar to 10-100 Myr. This target will also be ideal for northern-hemisphere, high-contrast imaging platforms to search for self-luminous, planetary mass companions residing in this system.

ID: 159528
Type: article
Authors: Brout, Dillon; Hinton, Samuel R.; Scolnic, Dan
Abstract: Recent cosmological analyses (e.g., JLA, Pantheon) of Type Ia supernovae (SNe Ia) have propagated systematic uncertainties into a covariance matrix and either binned or smoothed the systematic uncertainty vectors in redshift space. We demonstrate that systematic error budgets of these analyses can be improved by a factor of similar to 1.5 x with the use of unbinned and unsmoothed covariance matrices. To understand this, we employ a separate approach that simultaneously fits for cosmological parameters and additional self-calibrating scale parameters that constrain the size of each systematic. We show that the covariance-matrix approach and scale-parameter approach indeed yield equivalent results, implying that in both cases the data can self-calibrate certain systematic uncertainties, but that this ability is hindered when information is binned or smoothed in redshift space. We review the top systematic uncertainties in current analyses and find that the reduction of systematic uncertainties in the unbinned case depends on whether a systematic is solely degenerate with the cosmological model in redshift space or whether it can be described by additional correlations between supernova properties and luminosity. Furthermore, we show that the power of self-calibration increases with the size of the data set, which presents a tremendous opportunity for upcoming analyses of photometrically classified samples, like those of Legacy Survey of Space and Time (LSST) and the Nancy Grace Roman Telescope (NGRST). However, to take advantage of self-calibration in large, photometrically classified samples, we must first address the issue that binning is required in currently used photometric analysis methods.

ID: 159529
Type: article
Authors: Hunter, T. R.; Brogan, C. L.; De Buizer, J. M.; Towner, A. P. M.; Dowell, C. D.; MacLeod, G. C.; Stecklum, B.; Cyganowski, C. J.; El-Abd, S. J.; McGuire, B. A.
Abstract: In recent years, dramatic outbursts have been identified toward massive protostars via infrared and millimeter dust continuum and molecular maser emission. The longest lived outburst (>6 yr) persists in NGC 6334 I-MM1, a deeply embedded object with no near-IR counterpart. Using FORCAST and HAWC+ on SOFIA, we have obtained the first mid-IR images of this field since the outburst began. Despite being undetected in pre-outburst ground-based 18 mu m images, MM1 is now the brightest region at all three wavelengths (25, 37, and 53 mu m), exceeding the UCHII region MM3 (NGC 6334 F). Combining the SOFIA data with ALMA imaging at four wavelengths, we construct a spectral energy distribution of the combination of MM1 and the nearby hot core MM2. The best-fit Robitaille radiative transfer model yields a luminosity of (4.9 +/- 0.8) x 10(4) L (circle dot). Accounting for an estimated pre-outburst luminosity ratio MM1:MM2 = 2.1 +/- 0.4, the luminosity of MM1 has increased by a factor of 16.3 +/- 4.4. The pre-outburst luminosity implies a protostar of mass 6.7 M (circle dot), which can produce the ionizing photon rate required to power the pre-outburst HCHII region surrounding the likely outbursting protostar MM1B. The total energy and duration of the outburst exceed the S255IR-NIRS3 outburst by a factor of greater than or similar to 3, suggesting a different scale of event involving expansion of the protostellar photosphere (to greater than or similar to 20 R (circle dot)), thereby supporting a higher accretion rate (greater than or similar to 0.0023 M (circle dot) yr(-1)) and reducing the ionizing photon rate. In the grid of hydrodynamic models of Meyer et al., the combination of outburst luminosity and magnitude (3) places the NGC 6334 I-MM1 event in the region of moderate total accretion (similar to 0.1-0.3 M (circle dot)) and hence long duration (similar to 40-130 yr).

ID: 159530
Type: article
Authors: Kannan, Rahul; Vogelsberger, M.; Marinacci, F.; Sales, L., V.; Torrey, P.; Hernquist, L.
Abstract: Winds driven by stellar feedback are an essential part of the galactic ecosystem and are the main mechanism through which low-mass galaxies regulate their star formation. These winds are generally observed to be multiphase with detections of entrained neutral and molecular gas. They are also thought to enrich the circumgalactic medium around galaxies with metals and dust. This ejected dust encodes information about the integrated star formation and outflow history of the galaxy. Therefore it is important to understand how much dust is entrained and driven out of the disc by galactic winds. Here, we demonstrate that stellar feedback is efficient in driving dust-enriched winds and eject enough material to account for the amount of extraplanar dust observed in nearby galaxies. The amount of ejected dust depends on the sites from where they are launched, with dustier galaxies launching more dust-enriched outflows. Moreover, the outflowing cold and dense gas is significantly more dust enriched than the volume filling hot and tenuous material. These results provide an important new insight into the dynamics, structure, and composition of galactic winds and their role in determining the dust content of the extragalactic gas in galaxies.

ID: 159531
Type: article
Authors: Zerjal, Marusa; Rains, Adam D.; Ireland, Michael J.; Zhou, George; Kammerer, Jens; Wallace, Alex; Orenstein, Brendan J.; Nordlander, Thomas; Abbot, Harrison; Chang, Seo-Won
Abstract: In the Gaia era, the majority of stars in the Solar neighbourhood have parallaxes and proper motions precisely determined while spectroscopic age indicators are still missing for a large fraction of low-mass young stars. In this work, we select 756 overluminous late K and early M young star candidates in the southern sky and observe them over 64 nights with the ANU 2.3-m Telescope at Siding Spring Observatory using the Echelle (R = 24000) and Wide Field spectrographs (WiFeS, R = 3000-7000). Our selection is kinematically unbiased to minimize the preference against low-mass members of stellar associations that dissipate first and to include potential members of diffuse components. We provide measurements of H alpha and calcium H&K emission, as well as of Li i 6708 angstrom in absorption. This enables identification of stars as young as 10-30 Myr - a typical age range for stellar associations. We report on 346 stars showing detectable lithium absorption, 318 of which are not included in existing catalogues of young stars. We also report 125 additional stars in our sample presenting signs of stellar activity indicating youth but with no detectable lithium. Radial velocities are determined for WiFeS spectra with a precision of 3.2 kms(-1) and 1.5 kms(-1) for the Echelle sample.

ID: 159535
Type: article
Authors: Gieser, C.; Beuther, H.; Semenov, D.; Ahmadi, A.; Suri, S.; Moeller, T.; Beltran, M. T.; Klaassen, P.; Zhang, Q.; Urquhart, J. S.; Henning, Th; Feng, S.; Galvan-Madrid, R.; Magalhaes, V. de Souza; Moscadelli, L.; Longmore, S.; Leurini, S.; Kuiper, R.; Peters, T.; Menten, K. M.; Csengeri, T.; Fuller, G.; Wyrowski, F.; Lumsden, S.; Sanchez-Monge, A.; Maud, L.; Linz, H.; Palau, A.; Schilke, P.; Pety, J.; Pudritz, R.; Winters, J. M.; Pietu, V.
Abstract: Aims. Current star formation research centers the characterization of the physical and chemical properties of massive stars, which are in the process of formation, at the spatial resolution of individual high-mass cores. Methods. We use sub-arcsecond resolution (similar to 0 ''.4) observations with the NOrthern Extended Millimeter Array at 1.37 mm to study the dust emission and molecular gas of 18 high-mass star-forming regions. With distances in the range of 0.7-5.5 kpc, this corresponds to spatial scales down to 300-2300 au that are resolved by our observations. We combined the derived physical and chemical properties of individual cores in these regions to estimate their ages. The temperature structures of these regions are determined by fitting the H2CO and CH3CN line emission. The density profiles are inferred from the 1.37 mm continuum visibilities. The column densities of 11 different species are determined by fitting the emission lines with XCLASS. Results. Within the 18 observed regions, we identified 22 individual cores with associated 1.37 mm continuum emission and with a radially decreasing temperature profile. We find an average temperature power-law index of q = 0.4 +/- 0.1 and an average density power-law index of p = 2.0 +/- 0.2 on scales that are on the order of several 1000 au. Comparing these results with values of p derived from the literature presumes that the density profiles remain unchanged from clump to core scales. The column densities relative to N((CO)-O-18) between pairs of dense gas tracers show tight correlations. We applied the physical-chemical model MUlti Stage ChemicaL codE to the derived column densities of each core and find a mean chemical age of similar to 60 000 yr and an age spread of 20 000-100 000 yr. With this paper, we release all data products of the CORE project. Conclusions. The CORE sample reveals well-constrained density and temperature power-law distributions. Furthermore, we characterized a large variety in molecular richness that can be explained by an age spread that is then confirmed by our physical-chemical modeling. The hot molecular cores show the greatest number of emission lines, but we also find evolved cores at an evolutionary stage in which most molecules are destroyed and, thus, the spectra appear line-poor once again.

ID: 159537
Type: article
Authors: Sozzetti, A.; Damasso, M.; Bonomo, A. S.; Alibert, Y.; Sousa, S. G.; Adibekyan, V.; Zapatero Osorio, M. R.; Gonzalez Hernandez, J. I.; Barros, S. C. C.; Lillo-Box, J.; Stassun, K. G.; Winn, J.; Cristiani, S.; Pepe, F.; Rebolo, R.; Santos, N. C.; Allart, R.; Barclay, T.; Bouchy, F.; Cabral, A.; Ciardi, D.; Di Marcantonio, P.; D'Odorico, V.; Ehrenreich, D.; Fasnaugh, M.; Figueira, P.; Haldemann, J.; Jenkins, J. M.; Latham, D. W.; Lavie, B.; Lo Curto, G.; Lovis, C.; Martins, C. J. A. P.; Megevand, D.; Mehner, A.; Micela, G.; Molaro, P.; Nunes, N. J.; Oshagh, M.; Otegi, J.; Palle, E.; Poretti, E.; Ricker, G.; Rodriguez, D.; Seager, S.; Suarez Mascareno, A.; Twicken, J. D.; Udry, S.
Abstract: Context. Transiting sub-Neptune-type planets, with radii approximately between 2 and 4 R-circle plus, are of particular interest as their study allows us to gain insight into the formation and evolution of a class of planets that are not found in our Solar System.Aims. We exploit the extreme radial velocity (RV) precision of the ultra-stable echelle spectrograph ESPRESSO on the VLT to unveil the physical properties of the transiting sub-Neptune TOI-130 b, uncovered by the TESS mission orbiting the nearby, bright, late F-type star HD 5278 (TOI-130) with a period of P-b = 14.3 days. Methods. We used 43 ESPRESSO high-resolution spectra and broad-band photometry information to derive accurate stellar atmospheric and physical parameters of HD 5278. We exploited the TESS light curve and spectroscopic diagnostics to gauge the impact of stellar activity on the ESPRESSO RVs. We performed separate as well as joint analyses of the TESS photometry and the ESPRESSO RVs using fully Bayesian frameworks to determine the system parameters. Results. Based on the ESPRESSO spectra, the updated stellar parameters of HD 5278 are T-eff = 6203 +/- 64 K, log g = 4.50 +/- 0.11 dex, [Fe/H] = -0.12 +/- 0.04 dex, M-star=1.126(-0.035)(+0.036) M-circle dot, and R-star=1.194(-0.016)(+0.017) R star=1.194(-0.016)(+0.017) R-circle dot. We determine HD 5278 b's mass and radius to be M-b=7.8(-1.4)(+1.5) M-circle plus and R-b = 2.45 +/- 0.05R(circle plus). The derived mean density, rho(b)=2.9(-0.5)(+0.6) g cm(-3), is consistent with the bulk composition of a sub-Neptune with a substantial (similar to 30%) water mass fraction and with a gas envelope comprising similar to 17% of the measured radius. Given the host brightness and irradiation levels, HD 5278 b is one of the best targetsorbiting G-F primaries for follow-up atmospheric characterization measurements with HST and JWST. We discover a second, non-transiting companion in the system, with a period of P-c=40.87(-0.17)(+0.18) days and a minimum mass of M-c sini(c)=18.4(-1.9)(+1.8) M-circle plus. We study emerging trends in parameters space (e.g., mass, radius, stellar insolation, and mean density) of the growing population of transiting sub-Neptunes, and provide statistical evidence for a low occurrence of close-in, 10 - 15M(circle plus) companions around G-F primaries with T-eff greater than or similar to 5500 K.

ID: 159538
Type: article
Authors: Woelfer, L.; Facchini, S.; Kurtovic, N. T.; Teague, Richard; van Dishoeck, E. F.; Benisty, M.; Ercolano, B.; Lodato, G.; Miotello, A.; Rosotti, G.; Testi, L.; Gabellini, M. G. Ubeira
Abstract: Context. In recent years high-angular-resolution observations have revealed that circumstellar discs appear in a variety of shapes with diverse substructures being ubiquitous. This has given rise to the question of whether these substructures are triggered by planet-disc interactions. Besides direct imaging, one of the most promising methods to distinguish between different disc-shaping mechanisms is to study the kinematics of the gas disc. In particular, the deviations of the rotation profile from Keplerian velocity can be used to probe perturbations in the gas pressure profile that may be caused by embedded (proto-) planets. Aims. In this paper we aim to analyse the gas brightness temperature and kinematics of the transitional disc around the intermediate-mass star CQ Tau in order to resolve and characterise substructure in the gas caused by possible perturbers. Methods. For our analysis we used spatially resolved ALMA observations of the three CO isotopologues (CO)-C-12, (CO)-C-13, and (CO)-O-18 (J = 2-1) from the disc around CQ Tau. We further extracted robust line centroids for each channel map and fitted a number of Keplerian disc models to the velocity field. Results. The gas kinematics of the CQ Tau disc present non-Keplerian features, showing bent and twisted iso-velocity curves in (CO)-C-12 and (CO)-C-13. Significant spiral structures are detected between similar to 10 and 180 au in both the brightness temperature and the rotation velocity of (CO)-C-12 after subtraction of an azimuthally symmetric model, which may be tracing planet-disc interactions with an embedded planet or low-mass companion. We identify three spirals, two in the brightness temperature and one in the velocity residuals, spanning a large azimuth and radial extent. The brightness temperature spirals are morphologically connected to spirals observed in near-infrared scattered light in the same disc, indicating a common origin. Together with the observed large dust and gas cavity, these spiral structures support the hypothesis of a massive embedded companion in the CQ Tau disc.

ID: 159422
Type: article
Authors: Trifonov, T.; Caballero, J. A.; Morales, J. C.; Seifahrt, A.; Ribas, I.; Reiners, A.; Bean, J. L.; Luque, R.; Parviainen, H.; Pallé, E.; Stock, S.; Zechmeister, M.; Amado, P. J.; Anglada-Escudé, G.; Azzaro, M.; Barclay, T.; Béjar, V. J. S.; Bluhm, P.; Casasayas-Barris, N.; Cifuentes, C.; Collins, Karen A.; Collins, K. I.; Cortés-Contreras, M.; de Leon, J.; Dreizler, S.; Dressing, C. D.; Esparza-Borges, E.; Espinoza, N.; Fausnaugh, M.; Fukui, A.; Hatzes, A. P.; Hellier, C.; Henning, Th; Henze, C. E.; Herrero, E.; Jeffers, S. V.; Jenkins, J. M.; Jensen, E. L. N.; Kaminski, A.; Kasper, D.; Kossakowski, D.; Kürster, M.; Lafarga, M.; Latham, David W.; Mann, A. W.; Molaverdikhani, K.; Montes, D.; Montet, B. T.; Murgas, F.; Narita, N.; Oshagh, M.; Passegger, V. M.; Pollacco, D.; Quinn, Samuel N.; Quirrenbach, A.; Ricker, G. R.; Rodríguez López, C.; Sanz-Forcada, J.; Schwarz, R. P.; Schweitzer, A.; Seager, S.; Shporer, A.; Stangret, M.; Stürmer, J.; Tan, T. G.; Tenenbaum, P.; Twicken, J. D.; Vanderspek, R.; Winn, J. N.
Abstract: Spectroscopy of transiting exoplanets can be used to investigate their atmospheric properties and habitability. Combining radial velocity (RV) and transit data provides additional information on exoplanet physical properties. We detect a transiting rocky planet with an orbital period of 1.467 days around the nearby red dwarf star Gliese 486. The planet Gliese 486 b is 2.81 Earth masses and 1.31 Earth radii, with uncertainties of 5%, as determined from RV data and photometric light curves. The host star is at a distance of ~8.1 parsecs, has a J-band magnitude of ~7.2, and is observable from both hemispheres of Earth. On the basis of these properties and the planet's short orbital period and high equilibrium temperature, we show that this terrestrial planet is suitable for emission and transit spectroscopy.

ID: 159423
Type: article
Authors: Adams, C. B.; Alfaro, R.; Ambrosi, G.; Ambrosio, M.; Aramo, C.; Arlen, T.; Batista, P. I.; Benbow, Wystan; Bertucci, B.; Bissaldi, E.; Biteau, J.; Bitossi, M.; Boiano, A.; Bonavolontà, C.; Bose, R.; Bouvier, A.; Brill, A.; Brown, A. M.; Buckley, J. H.; Byrum, K.; Cameron, R. A.; Canestrari, R.; Capasso, M.; Caprai, M.; Covault, C. E.; Depaoli, D.; Errando, M.; Fegan, S.; Feng, Q.; Fiandrini, E.; Foote, G.; Fortin, Pascal; Funk, S.; Furniss, A.; Garfias, F.; Gent, A.; Giglietto, N.; Giordano, F.; Giro, E.; González, M. M.; Guarino, V.; Halliday, R.; Hervet, O.; Holder, J.; Hughes, Gareth; Humensky, T. B.; Ionica, M.; Iriarte, A.; Jin, W.; Johnson, C. A.; Kaaret, P.; Kieda, D.; Kim, B.; Kuznetsov, A.; Lapington, J. S.; Licciulli, F.; Loporchio, S.; Masone, V.; Meagher, K.; Meures, T.; Mode, B. A. W.; Mognet, S. A. I.; Mukherjee, R.; Nguyen, T.; Nieto, D.; Okumura, A.; Otte, N.; La Palombara, N.; Pantaleo, F. R.; Paoletti, R.; Pareschi, G.; Petrashyk, A.; Di Pierro, F.; Pueschel, E.; Reynolds, P. T.; Ribeiro, D.; Richards, G.; Roache, Emmet; Ross, D.; Rousselle, J.; Rugliancich, A.; Ruíz-Díaz-Soto, J.; Santander, M.; Schlenstedt, S.; Schneider, M.; Scuderi, S.; Shang, R.; Sironi, G.; Stevenson, B.; Stiaccini, L.; Tajima, H.; Taylor, L. P.; Thornhill, J.; Tosti, L.; Tovmassian, G.; Vagelli, V.; Valentino, M.; Vandenbroucke, J.; Vassiliev, V. V.; Di Venere, L.; Wakely, S. P.; Watson, J. J.; White, R.; Wilcox, P.; Williams, D. A.; Wood, M.; Yu, P.; Zink, A.
Abstract: The Schwarzschild-Couder Telescope (SCT) is a telescope concept proposed for the Cherenkov Telescope Array. It employs a dual-mirror optical design to remove comatic aberrations over an 8^∘ field of view, and a high-density silicon photomultiplier camera (with a pixel resolution of 4 arcmin) to record Cherenkov emission from cosmic ray and gamma-ray initiated particle cascades in the atmosphere. The prototype SCT (pSCT), comprising a 9.7 m diameter primary mirror and a partially instrumented camera with 1536 pixels, has been constructed at the Fred Lawrence Whipple Observatory. The telescope was inaugurated in January 2019, with commissioning continuing throughout 2019. We describe the first campaign of observations with the pSCT, conducted in January and February of 2020, and demonstrate the detection of gamma-ray emission from the Crab Nebula with a statistical significance of 8.6 σ .

ID: 159424
Type: article
Authors: Bonaca, Ana; Naidu, Rohan P.; Conroy, Charlie; Caldwell, Nelson; Cargile, Phillip A.; Han, Jiwon Jesse; Johnson, Benjamin D.; Kruijssen, J. M. Diederik; Myeong, G. C.; Speagle, Joshua S.; Ting, Yuan-Sen; Zaritsky, Dennis
Abstract: The origins of most stellar streams in the Milky Way are unknown. With improved proper motions provided by Gaia EDR3, we show that the orbits of 23 Galactic stellar streams are highly clustered in orbital phase space. Based on their energies and angular momenta, most streams in our sample can plausibly be associated with a specific (disrupted) dwarf galaxy host that brought them into the Milky Way. For eight streams we also identify likely globular cluster progenitors (four of these associations are reported here for the first time). Some of these stream progenitors are surprisingly far apart, displaced from their tidal debris by a few to tens of degrees. We identify stellar streams that appear spatially distinct, but whose similar orbits indicate they likely originate from the same progenitor. If confirmed as physical discontinuities, they will provide strong constraints on the mass loss from the progenitor. The nearly universal ex situ origin of existing stellar streams makes them valuable tracers of galaxy mergers and dynamical friction within the Galactic halo. Their phase-space clustering can be leveraged to construct a precise global map of dark matter in the Milky Way, while their internal structure may hold clues to the small-scale structure of dark matter in their original host galaxies.

ID: 159425
Type: article
Authors: Lee, Kin Long Kelvin; Changala, P. Bryan; Loomis, Ryan A.; Burkhardt, Andrew M.; Xue, Ci; Cordiner, Martin A.; Charnley, Steven B.; McCarthy, Michael C.; McGuire, Brett A.
Abstract: Using radio observations with the Green Bank Telescope, evidence has now been found for a second five-membered ring in the dense cloud Taurus Molecular Cloud-1 (TMC-1). Based on additional observations of an ongoing, large-scale, high-sensitivity spectral line survey (GOTHAM) at centimeter wavelengths toward this source, we have used a combination of spectral stacking, Markov Chain Monte Carlo (MCMC), and matched filtering techniques to detect 2-cyanocyclopentadiene, a low-lying isomer of 1-cyanocyclopentadiene, which was recently discovered there by the same methods. The new observational data also yield a considerably improved detection significance for the more stable isomer and evidence for several individual transitions between 23-32 GHz. Through our MCMC analysis, we derive cospatial, total column densities of 8.3 × 10¹¹ and 1.9 × 10¹¹ cm^-2 for 1- and 2-cyanocyclopentadiene, respectively, corresponding to a ratio of ∼4.4 favoring the former. The derived abundance ratios point toward a common formation pathway-most likely being cyanation of cyclopentadiene by analogy to benzonitrile.

ID: 159426
Type: article
Authors: Wang, Jingyi; Mastroserio, Guglielmo; Kara, Erin; García, Javier A.; Ingram, Adam; Connors, Riley; van der Klis, Michiel; Dauser, Thomas; Steiner, James F.; Buisson, Douglas J. K.; Homan, Jeroen; Lucchini, Matteo; Fabian, Andrew C.; Bright, Joe; Fender, Rob; Cackett, Edward M.; Remillard, Ron A.
Abstract: We analyze five epochs of Neutron star Interior Composition Explorer (NICER) data of the black hole X-ray binary MAXI J1820+070 during the bright hard-to-soft state transition in its 2018 outburst with both reflection spectroscopy and Fourier-resolved timing analysis. We confirm the previous discovery of reverberation lags in the hard state, and find that the frequency range where the (soft) reverberation lag dominates decreases with the reverberation lag amplitude increasing during the transition, suggesting an increasing X-ray emitting region, possibly due to an expanding corona. By jointly fitting the lag-energy spectra in a number of broad frequency ranges with the reverberation model reltrans, we find the increase in reverberation lag is best described by an increase in the X-ray coronal height. This result, along with the finding that the corona contracts in the hard state, suggests a close relationship between spatial extent of the X-ray corona and the radio jet. We find the corona expansion (as probed by reverberation) precedes a radio flare by ∼5 days, which may suggest that the hard-to-soft transition is marked by the corona expanding vertically and launching a jet knot that propagates along the jet stream at relativistic velocities.

ID: 159427
Type: article
Authors: Takemura, Hideaki; Nakamura, Fumitaka; Kong, Shuo; Arce, Héctor G.; Carpenter, John M.; Ossenkopf-Okada, Volker; Klessen, Ralf; Sanhueza, Patricio; Shimajiri, Yoshito; Tsukagoshi, Takashi; Kawabe, Ryohei; Ishii, Shun; Dobashi, Kazuhito; Shimoikura, Tomomi; Goldsmith, Paul F.; Sánchez-Monge, Álvaro; Kauffmann, Jens; Pillai, Thushara G. S.; Padoan, Paolo; Ginsberg, Adam; Smith, Rowan J.; Bally, John; Mairs, Steve; Pineda, Jaime E.; Lis, Dariusz C.; Burkhart, Blakesley; Schilke, Peter; Chen, Hope How-Huan; Isella, Andrea; Friesen, Rachel K.; Goodman, Alyssa A.; Harper, Doyal A.
Abstract: Applying dendrogram analysis to the CARMA-NRO C¹⁸O (J = 1-0) data having an angular resolution of ∼8″, we identified 692 dense cores in the Orion Nebula Cluster region. Using this core sample, we compare the core and initial stellar mass functions in the same area to quantify the step from cores to stars. About 22% of the identified cores are gravitationally bound. The derived core mass function (CMF) for starless cores has a slope similar to Salpeter's stellar initial mass function (IMF) for the mass range above 1 M_⊙, consistent with previous studies. Our CMF has a peak at a subsolar mass of ∼0.1 M_⊙, which is comparable to the peak mass of the IMF derived in the same area. We also find that the current star formation rate is consistent with the picture in which stars are born only from self-gravitating starless cores. However, the cores must gain additional gas from the surroundings to reproduce the current IMF (e.g., its slope and peak mass), because the core mass cannot be accreted onto the star with 100% efficiency. Thus, the mass accretion from the surroundings may play a crucial role in determining the final stellar masses of stars.

ID: 159428
Type: article
Authors: Xiang, Danfeng; Wang, Xiaofeng; Lin, Weili; Mo, Jun; Lin, Han; Burke, Jamison; Hiramatsu, Daichi; Hosseinzadeh, Griffin; Howell, D. Andrew; McCully, Curtis; Valenti, Stefan; Vinkó, József; Wheeler, J. Craig; Ehgamberdiev, Shuhrat A.; Mirzaqulov, Davron; Bódi, Attila; Bognár, Zsófia; Cseh, Borbála; Hanyecz, Ottó; Ignácz, Bernadett; Kalup, Csilla; Könyves-Tóth, Réka; Kriskovics, Levente; Ordasi, András; Pál, András; Sárneczky, Krisztián; Seli, Bálint; Szakáts, Róbert; Arranz-Heras, T.; Benavides-Palencia, R.; Cejudo-Martínez, D.; De la Fuente-Fernández, P.; Escartín-Pérez, A.; García-De la Cuesta, F.; González-Carballo, J. L.; González-Farfán, R.; Limón-Martínez, F.; Mantero, A.; Naves-Nogués, R.; Morales-Aimar, M.; Ruíz-Ruíz, V. R.; Soldán-Alfaro, F. C.; Valero-Pérez, J.; Violat-Bordonau, F.; Zhang, Tianmeng; Zhang, Jujia; Li, Xue; Chen, Zhihao; Sai, Hanna; Li, Wenxiong
Abstract: We present our photometric and spectroscopic observations of the peculiar transient AT2018cow. The multiband photometry covers from peak to ∼70 days, and the spectroscopy ranges from 5 to ∼50 days. The rapid rise (t_r ≲ 2.9 days), high luminosity (M_V,peak ∼ -20.8 mag), and fast decline after peak make AT2018cow stand out from any other optical transients, whereas we find that its light curves show a high resemblance to those of Type Ibn supernovae. Moreover, the spectral energy distribution remains at a high temperature of ∼14,000 K at t > 15 days after discovery. The spectra are featureless in the first 10 days, while some broad emission lines due to H, He, C, and O emerge later, with velocity declining from ∼14,000 to ∼3000 km s^-1 at the end of our observations. Narrow and weak He I emission lines emerge in the spectra at t > 20 days after discovery. These emission lines are reminiscent of the features seen in interacting supernovae like the Type Ibn and IIn subclasses. We fit the bolometric light curves with a model of circumstellar interaction and radioactive decay of ⁵⁶Ni and find a good fit with ejecta mass M_ej ∼ 3.16 M_⊙, circumstellar medium (CSM) mass M_CSM ∼ 0.04 M_⊙, and ejected ⁵⁶Ni mass ${M}_{{}^{56}\mathrm{Ni}}\sim 0.23$ M_⊙. The CSM shell might be formed in an eruptive mass ejection of the progenitor star. Furthermore, the host environment of AT2018cow implies a connection of AT2018cow with massive stars. Combining observational properties and the light-curve fitting results, we conclude that AT2018cow might be a peculiar interacting supernova that originated from a massive star.

ID: 159429
Type: article
Authors: Tartaglia, L.; Sand, D. J.; Groh, J. H.; Valenti, S.; Wyatt, S. D.; Bostroem, K. A.; Brown, P. J.; Yang, S.; Burke, J.; Chen, T. -W; Davis, S.; Förster, F.; Galbany, L.; Haislip, J.; Hiramatsu, D.; Hosseinzadeh, Griffin; Howell, D. A.; Hsiao, E. Y.; Jha, S. W.; Kouprianov, V.; Kuncarayakti, H.; Lyman, J. D.; McCully, C.; Phillips, M. M.; Rau, A.; Reichart, D. E.; Shahbandeh, M.; Strader, J.
Abstract: We present high-cadence, comprehensive data on the nearby (D ≃ 33 Mpc) Type II supernova (SN II) 2017ahn, discovered within about one day of the explosion, from the very early phases after explosion to the nebular phase. The observables of SN 2017ahn show a significant evolution over the ≃470 days of our follow-up campaign, first showing prominent, narrow Balmer lines and other high-ionization features purely in emission (i.e., flash spectroscopy features), which progressively fade and lead to a spectroscopic evolution similar to that of more canonical SNe II. Over the same period, the decline of the light curves in all bands is fast, resembling the photometric evolution of linearly declining H-rich core-collapse SNe. The modeling of the light curves and early flash spectra suggests that a complex circumstellar medium surrounds the progenitor star at the time of explosion, with a first dense shell produced during the very late stages of its evolution that is swept up by the rapidly expanding ejecta within the first ∼6 days of the SN evolution, while signatures of interaction are observed also at later phases. Hydrodynamical models support the scenario in which linearly declining SNe II are predicted to arise from massive yellow super- or hypergiants depleted of most of their hydrogen layers.

ID: 159430
Type: article
Authors: Connors, Riley M. T.; García, Javier A.; Tomsick, John; Hare, Jeremy; Dauser, Thomas; Grinberg, Victoria; Steiner, James F.; Mastroserio, Guglielmo; Sridhar, Navin; Fabian, Andrew C.; Jiang, Jiachen; Parker, Michael L.; Harrison, Fiona; Kallman, Timothy R.
Abstract: We present the analysis of X-ray observations of the black hole binary 4U 1630-47 using relativistic reflection spectroscopy. We use archival data from the Rossi X-ray Timing Explorer, Neil Gehrels Swift Observatory, and Nuclear Spectroscopic Telescope Array observatories, taken during different outbursts of the source between 1998 and 2015. Our modeling includes two relatively new advances in modern reflection codes: high-density disks, and returning thermal disk radiation. Accretion disks around stellar-mass black holes are expected to have densities well above the standard value assumed in traditional reflection models (i.e., n_e ∼ 10¹⁵ cm^-3). New high-density reflection models have important implications in the determination of disk truncation (i.e., the disk inner radius). This is because one must retain self-consistency in the irradiating flux and corresponding disk ionization state, which is a function of disk density and system geometry. We find that the disk density is n_e ≥ 10²⁰ cm^-3 across all spectral states. This density, combined with our constraints on the ionization state of the material, implies an irradiating flux impinging on the disk that is consistent with the expected theoretical estimates. Returning thermal disk radiation-the fraction of disk photons that bend back to the disk producing additional reflection components-is expected predominantly in the soft state. We show that returning radiation models indeed provide a better fit to the soft-state data, reinforcing previous results that show that in the soft state, the irradiating continuum may be blackbody emission from the disk itself.

ID: 159431
Type: article
Authors: Zhao, Xueshan; Gou, Lijun; Dong, Yanting; Zheng, Xueying; Steiner, James F.; Miller-Jones, James C. A.; Bahramian, Arash; Orosz, Jerome A.; Feng, Ye
Abstract: Cygnus X-1 is a well-studied persistent black hole X-ray binary. Recently, the three parameters needed to estimate the black hole spin of this system, namely the black hole mass M, the orbital inclination i, and the source distance D, have been updated. In this work we redetermine the spin parameter using the continuum-fitting technique for those updated parameter values. Based on the assumption that the spin axis of the black hole is aligned with the orbital plane, we fit the thermal disk component to a fully relativistic thin accretion disk model. The error in the spin estimate arising from the combined observational uncertainties is obtained via Monte Carlo simulations. We demonstrate that, without considering the counteracting torque effect, the new spin parameter is constrained to be a_* > 0.9985 (3σ), which confirms that the spin of the black hole in Cygnus X-1 is extreme.

ID: 159432
Type: article
Authors: Lu, Xing; Li, Shanghuo; Ginsburg, Adam; Longmore, Steven N.; Kruijssen, J. M. Diederik; Walker, Daniel L.; Feng, Siyi; Zhang, Qizhou; Battersby, Cara; Pillai, Thushara; Mills, Elisabeth A. C.; Kauffmann, Jens; Cheng, Yu; Inutsuka, Shu-ichiro
Abstract: We observe 1.3 mm spectral lines at 2000 au resolution toward four massive molecular clouds in the Central Molecular Zone (CMZ) of the Galaxy to investigate their star formation activities. We focus on several potential shock tracers that are usually abundant in protostellar outflows, including SiO, SO, CH₃OH, H₂CO, HC₃N, and HNCO. We identify 43 protostellar outflows, including 37 highly likely ones and 6 candidates. The outflows are found toward both known high-mass star-forming cores and less massive, seemingly quiescent cores, while 791 out of the 834 cores identified based on the continuum do not have detected outflows. The outflow masses range from less than 1 M_⊙ to a few tens of M_⊙, with typical uncertainties of a factor of 70. We do not find evidence of disagreement between relative molecular abundances in these outflows and in nearby analogs such as the well-studied L1157 and NGC 7538S outflows. The results suggest that (i) protostellar accretion disks driving outflows ubiquitously exist in the CMZ environment, (ii) the large fraction of candidate starless cores is expected if these clouds are at very early evolutionary phases, with a caveat on the potential incompleteness of the outflows, (iii) high-mass and low-mass star formation is ongoing simultaneously in these clouds, and (iv) current data do not show evidence of a difference between the shock chemistry in the outflows that determines the molecular abundances in the CMZ environment and in nearby clouds.

ID: 159433
Type: article
Authors: Olguin, Fernando A.; Sanhueza, Patricio; Guzmán, Andrés E.; Lu, Xing; Saigo, Kazuya; Zhang, Qizhou; Silva, Andrea; Chen, Huei-Ru Vivien; Li, Shanghuo; Ohashi, Satoshi; Nakamura, Fumitaka; Sakai, Takeshi; Wu, Benjamin
Abstract: We observed the high-mass star-forming region G335.579-0.292 with the Atacama Large Millimeter/submillimeter Array (ALMA) at 226 GHz with an angular resolution of 0"3 (∼1000 au resolution at the source distance). G335.579-0.292 hosts one of the most massive cores in the Galaxy (G335-MM1). The continuum emission shows that G335-MM1 fragments into at least five sources, while molecular line emission is detected in two of the continuum sources (ALMA1 and ALMA3). We found evidence of large- and small-scale infall in ALMA1 revealed by an inverse P-Cygni profile and the presence of a blueshifted spot at the center of the first moment map of the CH₃CN emission. In addition, hot gas expansion in the innermost region is unveiled by a redshifted spot in the first moment map of HDCO and (CH₃)₂CO (both with E_u > 1100 K). Our modeling reveals that this expansion motion originates close to the central source, likely due to reversal of the accretion flow induced by the expansion of the H II region, while infall and rotation motions originate in the outer regions. ALMA3 shows clear signs of rotation, with a rotation axis inclination with respect to the line of sight close to 90°, and a system mass (disk + star) in the range of 10-30 M_☉.

ID: 159434
Type: article
Authors: Law, Charles J.; Zhang, Qizhou; Öberg, Karin I.; Galván-Madrid, Roberto; Keto, Eric; Liu, Hauyu Baobab; Ho, Paul T. P.
Abstract: Massive star-forming regions exhibit an extremely rich and diverse chemistry, which in principle provides a wealth of molecular probes, as well as laboratories for interstellar prebiotic chemistry. Since the chemical structure of these sources displays substantial spatial variation among species on small scales (≲10⁴ au), high-angular-resolution observations are needed to connect chemical structures to local environments and inform astrochemical models of massive star formation. To address this, we present ALMA 1.3 mm observations toward OB cluster-forming region G10.6-0.4 (hereafter "G10.6") at a resolution of 0"14 (700 au). We find highly structured emission from complex organic molecules (COMs) throughout the central 20,000 au, including two hot molecular cores and several shells or filaments. We present spatially resolved maps of rotational temperature and column density for a large sample of COMs and warm gas tracers. These maps reveal a range of gas substructure in both O- and N-bearing species. We identify several spatial correlations that can be explained by existing models for the formation of COMs, including NH₂CHO/HNCO and CH₃OCHO/CH₃OCH₃, but also observe unexpected distributions and correlations that suggest that our current understanding of COM formation is far from complete. Importantly, complex chemistry is observed throughout G10.6, rather than being confined to hot cores. The COM composition appears to be different in the cores compared to the more extended structures, which illustrates the importance of high-spatial-resolution observations of molecular gas in elucidating the physical and chemical processes associated with massive star formation.

ID: 159435
Type: article
Authors: Yue, Nan-Nan; Li, Di; Zhang, Qi-Zhou; Zhu, Lei; Henshaw, Jonathan; Mardones, Diego; Ren, Zhi-Yuan
Abstract: We report here Atacama Large Millimeter/submillimeter Array (ALMA) N₂H⁺ (1-0) images of the Orion Molecular Cloud 2 and 3 (OMC-2/3) with high angular resolution (3″ or 1200 au) and high spatial dynamic range. Combining a dataset from the ALMA main array, Atacama Compact Array (ACA), Nobeyama 45-m Telescope and Very Large Array (VLA) (providing temperature measurement on matching scales), we find that most of the dense gas in OMC-2/3 is subsonic (σ_NT / C_s = 0.62) with a mean line width (Δυ) of 0.39 km s^-1 full width at half maximum (FWHM). This is markedly different from the majority of previous observations of massive star-forming regions. In contrast, line widths from the Nobeyama Telescope are transonic at 0.69 km s^-1 (σ_NT / C_s = 1.08). We demonstrated that the larger line widths obtained by the single-dish telescope arose from unresolved sub-structures within their respective beams. The dispersions from larger scales σ_ls (as traced by the Nobeyama Telescope) can be decomposed into three components such that ${\sigma }_{{\rm{ls}}}^{2}={\sigma }_{{\rm{ss}}}^{2}+{\sigma }_{{\rm{bm}}}^{2}+{\sigma }_{{\rm{rd}}}^{2}$ , where small-scale σ_ss is the line dispersion of each ALMA beam, bulk motion σ_bm is dispersion between peak velocity of each ALMA beam and σ_rd is the residual dispersion. Such decomposition, though purely empirical, appears to be robust throughout our data cubes. Apparent supersonic line widths, commonly found in massive molecular clouds, are thus likely due to the effect of poor spatial resolution. The observed non-thermal line dispersion (sometimes referred to as 'turbulence') transits from supersonic to subsonic at ∼ 0.05 pc scales in the OMC-2/3 region. Such transition could be commonly found with sufficient spatial (not just angular) resolution, even in regions with massive young clusters, such as the Orion molecular clouds studied here.

ID: 159436
Type: article
Authors: Binder, Breanna A.; Sy, Janelle M.; Eracleous, Michael; Christodoulou, Dimitris M.; Bhattacharya, Sayantan; Cappallo, Rigel; Laycock, Silas; Plucinsky, Paul P.; Williams, Benjamin F.
Abstract: We present new X-ray and UV observations of the Wolf-Rayet + black hole (BH) binary system NGC 300 X-1 with the Chandra X-ray Observatory and the Hubble Space Telescope Cosmic Origins Spectrograph. When combined with archival X-ray observations, our X-ray and UV observations sample the entire binary orbit, providing clues to the system geometry and interaction between the BH accretion disk and the donor star wind. We measure a binary orbital period of 32.7921 ± 0.0003 hr, in agreement with previous studies, and perform phase-resolved spectroscopy using the X-ray data. The X-ray light curve reveals a deep eclipse, consistent with inclination angles of i = 60°-75°, and a pre-eclipse excess consistent with an accretion stream impacting the disk edge. We further measure radial velocity variations for several prominent far-UV spectral lines, most notably H II λ1640 and C IV λ1550. We find that the He II emission lines systematically lag the expected Wolf-Rayet star orbital motion by a phase difference of Δφ ∼ 0.3, while C IV λ1550 matches the phase of the anticipated radial velocity curve of the Wolf-Rayet donor. We assume the C IV λ1550 emission line follows a sinusoidal radial velocity curve (semi-amplitude = 250 km s^-1) and infer a BH mass of 17 ± 4 M_⊙. Our observations are consistent with the presence of a wind-Roche lobe overflow accretion disk, where an accretion stream forms from gravitationally focused wind material and impacts the edge of the BH accretion disk.

ID: 159437
Type: article
Authors: Sano, Hidetoshi; Tsuge, Kisetsu; Tokuda, Kazuki; Muraoka, Kazuyuki; Tachihara, Kengo; Yamane, Yumiko; Kohno, Mikito; Fujita, Shinji; Enokiya, Rei; Rowell, Gavin; Maxted, Nigel; Filipović, Miroslav D.; Knies, Jonathan; Sasaki, Manami; Onishi, Toshikazu; Plucinsky, Paul P.; Fukui, Yasuo
Abstract: We report the first evidence for high-mass star formation triggered by collisions of molecular clouds in M 33. Using the Atacama Large Millimeter/submillimeter Array, we spatially resolved filamentary structures of giant molecular cloud 37 in M 33 using ¹²CO(J = 2-1), ¹³CO(J = 2-1), and C¹⁸O(J = 2-1) line emission at a spatial resolution of ∼2 pc. There are two individual molecular clouds with a systematic velocity difference of ∼6 km s^-1. Three continuum sources representing up to ∼10 high-mass stars with spectral types of B0V-O7.5V are embedded within the densest parts of molecular clouds bright in the C¹⁸O(J = 2-1) line emission. The two molecular clouds show a complementary spatial distribution with a spatial displacement of ∼6.2 pc, and show a V-shaped structure in the position-velocity diagram. These observational features traced by CO and its isotopes are consistent with those in high-mass star-forming regions created by cloud-cloud collisions in the Galactic and Magellanic Cloud H II regions. Our new finding in M 33 indicates that cloud-cloud collision is a promising process for triggering high-mass star formation in the Local Group.

ID: 159438
Type: article
Authors: Vantyghem, A. N.; McNamara, B. R.; O'Dea, C. P.; Baum, S. A.; Combes, F.; Edge, A. C.; Fabian, A. C.; McDonald, Michael; Nulsen, P. E. J.; Russell, H. R.; Salomé, P.
Abstract: We present a recent Atacama Large Millimeter/submillimeter Array observation of the CO(1-0) line emission in the central galaxy of the Zw 3146 galaxy cluster (z = 0.2906). We also present updated X-ray cavity measurements from archival Chandra observations. The 5 × 10¹⁰ M_⊙ supply of molecular gas, which is confined to the central 4 kpc, is marginally resolved into three extensions that are reminiscent of the filaments observed in similar systems. No velocity structure that would be indicative of ordered motion is observed. The three molecular extensions all trail X-ray cavities, and are potentially formed from the condensation of intracluster gas lifted in the wakes of the rising bubbles. Many cycles of feedback would be required to account for the entire molecular gas reservoir. The molecular gas and continuum source are mutually offset by 2.6 kpc, with no detected line emission coincident with the continuum source. It is the molecular gas, not the continuum source, that lies at the gravitational center of the brightest cluster galaxy. As the brightest cluster galaxy contains possible tidal features, the displaced continuum source may correspond to the nucleus of a merging galaxy. We also discuss the possibility that a gravitational wave recoil following a black hole merger may account for the displacement.

ID: 159439
Type: article
Authors: Somboonpanyakul, Taweewat; McDonald, Michael A.; Gaspari, Massimo; Stalder, Brian; Stark, Antony A.
Abstract: We present optical follow-up observations for candidate clusters in the Clusters Hiding in Plain Sight survey, which is designed to find new galaxy clusters with extreme central galaxies that were misidentified as bright isolated sources in the ROSAT All-Sky Survey catalog. We identify 11 cluster candidates around X-ray, radio, and mid-IR-bright sources, including six well-known clusters, two false associations of foreground and background clusters, and three new candidates, which are observed further with Chandra. Of the three new candidates, we confirm two newly discovered galaxy clusters: CHIPS 1356-3421 and CHIPS 1911+4455. Both clusters are luminous enough to be detected in the ROSAT All-Sky Survey data if not because of their bright central cores. CHIPS 1911+4455 is similar in many ways to the Phoenix cluster, but with a highly disturbed X-ray morphology on large scales. We find the occurrence rate for clusters that would appear to be X-ray-bright point sources in the ROSAT All-Sky Survey (and any surveys with similar angular resolution) to be 2% ± 1%, and the occurrence rate of clusters with runaway cooling in their cores to be <1%, consistent with predictions of chaotic cold accretion. With the number of new groups and clusters predicted to be found with eROSITA, the population of clusters that appear to be point sources (due to a central QSO or a dense cool core) could be around 2000. Finally, this survey demonstrates that the Phoenix cluster is likely the strongest cool core at z < 0.7-anything more extreme would have been found in this survey.

ID: 159440
Type: article
Authors: Lagioia, E. P.; Milone, A. P.; Marino, A. F.; Tailo, M.; Renzini, A.; Carlos, M.; Cordoni, G.; Dondoglio, E.; Jang, S.; Karakas, A.; Dotter, Aaron
Abstract: Multiple stellar populations (MPs) are a distinct characteristic of globular clusters (GCs). Their general properties have been widely studied among main-sequence, red giant branch (RGB), and horizontal branch (HB) stars, but a common framework is still missing at later evolutionary stages. We studied the MP phenomenon along the asymptotic giant branch (AGB) sequences in 58 GCs, observed with the Hubble Space Telescope in UV and optical filters. Using UV-optical color-magnitude diagrams, we selected the AGB members of each cluster and identified the AGB candidates of the metal-enhanced population in type II GCs. We studied the photometric properties of the AGB stars and compared them to theoretical models derived from synthetic spectral analysis. We observed the following features: (i) the spread of AGB stars in photometric indices sensitive to variations of light elements and helium is typically larger than that expected from photometric errors; (ii) the fraction of metal-enhanced stars in the AGB is lower than that in the RGB in most of the type II GCs; (iii) the fraction of 1G stars derived from the chromosome map of AGB stars in 15 GCs is larger than that of RGB stars; and (v) the AGB/HB frequency correlates with the average mass of the most helium-enriched population. These findings represent clear evidence of the presence of MPs along the AGB of Galactic GCs and indicate that a significant fraction of helium-enriched stars, which have lower mass in the HB, do not evolve to the AGB phase, leaving the HB sequence toward higher effective temperatures, as predicted by the AGB manqué scenario.

ID: 159441
Type: article
Authors: Goddi, Ciriaco; Martí-Vidal, Iván; Messias, Hugo; Bower, Geoffrey C.; Broderick, Avery E.; Dexter, Jason; Marrone, Daniel P.; Moscibrodzka, Monika; Nagai, Hiroshi; Algaba, Juan Carlos; Asada, Keiichi; Crew, Geoffrey B.; Gómez, José L.; Impellizzeri, C. M. Violette; Janssen, Michael; Kadler, Matthias; Krichbaum, Thomas P.; Lico, Rocco; Matthews, Lynn D.; Nathanail, Antonios; Ricarte, Angelo; Ros, Eduardo; Younsi, Ziri; Akiyama, Kazunori; Alberdi, Antxon; Alef, Walter; Anantua, Richard; Azulay, Rebecca; Baczko, Anne-Kathrin; Ball, David; Baloković, Mislav; Barrett, John; Benson, Bradford A.; Bintley, Dan; Blackburn, Lindy; Blundell, Raymond; Boland, Wilfred; Bouman, Katherine L.; Boyce, Hope; Bremer, Michael; Brinkerink, Christiaan D.; Brissenden, Roger; Britzen, Silke; Broguiere, Dominique; Bronzwaer, Thomas; Byun, Do-Young; Carlstrom, John E.; Chael, Andrew; Chan, Chi-kwan; Chatterjee, Shami; Chatterjee, Koushik; Chen, Ming-Tang; Chen, Yongjun; Chesler, Paul M.; Cho, Ilje; Christian, Pierre; Conway, John E.; Cordes, James M.; Crawford, Thomas M.; Cruz-Osorio, Alejandro; Cui, Yuzhu; Davelaar, Jordy; De Laurentis, Mariafelicia; Deane, Roger; Dempsey, Jessica; Desvignes, Gregory; Doeleman, Sheperd S.; Eatough, Ralph P.; Falcke, Heino; Farah, Joseph; Fish, Vincent L.; Fomalont, Ed; Ford, H. Alyson; Fraga-Encinas, Raquel; Freeman, William T.; Friberg, Per; Fromm, Christian M.; Fuentes, Antonio; Galison, Peter; Gammie, Charles F.; García, Roberto; Gentaz, Olivier; Georgiev, Boris; Gold, Roman; Gómez-Ruiz, Arturo I.; Gu, Minfeng; Gurwell, Mark; Hada, Kazuhiro; Haggard, Daryl; Hecht, Michael H.; Hesper, Ronald; Ho, Luis C.; Ho, Paul; Honma, Mareki; Huang, Chih-Wei L.; Huang, Lei; Hughes, David H.; Inoue, Makoto; Issaoun, Sara; James, David J.; Jannuzi, Buell T.; Jeter, Britton; Jiang, Wu; Jimenez-Rosales, Alejandra; Johnson, Michael D.; Jorstad, Svetlana; Jung, Taehyun; Karami, Mansour; Karuppusamy, Ramesh; Kawashima, Tomohisa; Keating, Garrett K.; Kettenis, Mark; Kim, Dong-Jin; Kim, Jae-Young; Kim, Jongsoo; Kim, Junhan; Kino, Motoki; Koay, Jun Yi; Kofuji, Yutaro; Koch, Patrick M.; Koyama, Shoko; Kramer, Michael; Kramer, Carsten; Kuo, Cheng-Yu; Lauer, Tod R.; Lee, Sang-Sung; Levis, Aviad; Li, Yan-Rong; Li, Zhiyuan; Lindqvist, Michael; Lindahl, Greg; Liu, Jun; Liu, Kuo; Liuzzo, Elisabetta; Lo, Wen-Ping; Lobanov, Andrei P.; Loinard, Laurent; Lonsdale, Colin; Lu, Ru-Sen; MacDonald, Nicholas R.; Mao, Jirong; Marchili, Nicola; Markoff, Sera; Marscher, Alan P.; Matsushita, Satoki; Medeiros, Lia; Menten, Karl M.; Mizuno, Izumi; Mizuno, Yosuke; Moran, James M.; Moriyama, Kotaro; Müller, Cornelia; Musoke, Gibwa; Mejías, Alejandro Mus; Nagar, Neil M.; Nakamura, Masanori; Narayan, Ramesh; Narayanan, Gopal; Natarajan, Iniyan; Neilsen, Joey; Neri, Roberto; Ni, Chunchong; Noutsos, Aristeidis; Nowak, Michael A.; Okino, Hiroki; Olivares, Héctor; Ortiz-León, Gisela N.; Oyama, Tomoaki; Özel, Feryal; Palumbo, Daniel C. M.; Park, Jongho; Patel, Nimesh; Pen, Ue-Li; Pesce, Dominic W.; Piétu, Vincent; Plambeck, Richard; PopStefanija, Aleksandar; Porth, Oliver; Pötzl, Felix M.; Prather, Ben; Preciado-López, Jorge A.; Psaltis, Dimitrios; Pu, Hung-Yi; Ramakrishnan, Venkatessh; Rao, Ramprasad; Rawlings, Mark G.; Raymond, Alexander W.; Rezzolla, Luciano; Ripperda, Bart; Roelofs, Freek; Rogers, Alan; Rose, Mel; Roshanineshat, Arash; Rottmann, Helge; Roy, Alan L.; Ruszczyk, Chet; Rygl, Kazi L. J.; Sánchez, Salvador; Sánchez-Arguelles, David; Sasada, Mahito; Savolainen, Tuomas; Schloerb, F. Peter; Schuster, Karl-Friedrich; Shao, Lijing; Shen, Zhiqiang; Small, Des; Sohn, Bong Won; SooHoo, Jason; Sun, He; Tazaki, Fumie; Tetarenko, Alexandra J.; Tiede, Paul; Tilanus, Remo P. J.; Titus, Michael; Toma, Kenji; Torne, Pablo; Trent, Tyler; Traianou, Efthalia; Trippe, Sascha; van Bemmel, Ilse; van Langevelde, Huib Jan; van Rossum, Daniel R.; Wagner, Jan; Ward-Thompson, Derek; Wardle, John; Weintroub, Jonathan; Wex, Norbert; Wharton, Robert; Wielgus, Maciek; Wong, George N.; Wu, Qingwen; Yoon, Doosoo; Young, André; Young, Ken; Yuan, Feng; Yuan, Ye-Fei; Zensus, J. Anton; Zhao, Guang-Yao; Zhao, Shan-Shan; Bruni, Gabriele; Gopakumar, A.; Hernández-Gómez, Antonio; Herrero-Illana, Ruben; Ingram, Adam; Komossa, S.; Kovalev, Y. Y.; Muders, Dirk; Perucho, Manel; Rösch, Florian; Valtonen, Mauri
Abstract: We present the results from a full polarization study carried out with the Atacama Large Millimeter/submillimeter Array (ALMA) during the first Very Long Baseline Interferometry (VLBI) campaign, which was conducted in 2017 April in the λ3 mm and λ1.3 mm bands, in concert with the Global mm-VLBI Array (GMVA) and the Event Horizon Telescope (EHT), respectively. We determine the polarization and Faraday properties of all VLBI targets, including Sgr A*, M87, and a dozen radio-loud active galactic nuclei (AGNs), in the two bands at several epochs in a time window of 10 days. We detect high linear polarization fractions (2%-15%) and large rotation measures (RM > 10^3.3-10^5.5 rad m^-2), confirming the trends of previous AGN studies at millimeter wavelengths. We find that blazars are more strongly polarized than other AGNs in the sample, while exhibiting (on average) order-of-magnitude lower RM values, consistent with the AGN viewing angle unification scheme. For Sgr A* we report a mean RM of (-4.2 ± 0.3) × 10⁵ rad m^-2 at 1.3 mm, consistent with measurements over the past decade and, for the first time, an RM of (-2.1 ± 0.1) × 10⁵ rad m^-2 at 3 mm, suggesting that about half of the Faraday rotation at 1.3 mm may occur between the 3 mm photosphere and the 1.3 mm source. We also report the first unambiguous measurement of RM toward the M87 nucleus at millimeter wavelengths, which undergoes significant changes in magnitude and sign reversals on a one year timescale, spanning the range from -1.2 to 0.3 × 10⁵ rad m^-2 at 3 mm and -4.1 to 1.5 × 10⁵ rad m^-2 at 1.3 mm. Given this time variability, we argue that, unlike the case of Sgr A*, the RM in M87 does not provide an accurate estimate of the mass accretion rate onto the black hole. We put forward a two-component model, comprised of a variable compact region and a static extended region, that can simultaneously explain the polarimetric properties observed by both the EHT (on horizon scales) and ALMA (which observes the combined emission from both components). These measurements provide critical constraints for the calibration, analysis, and interpretation of simultaneously obtained VLBI data with the EHT and GMVA.

ID: 159442
Type: article
Authors: Event Horizon Telescope Collaboration; Akiyama, Kazunori; Algaba, Juan Carlos; Alberdi, Antxon; Alef, Walter; Anantua, Richard; Asada, Keiichi; Azulay, Rebecca; Baczko, Anne-Kathrin; Ball, David; Baloković, Mislav; Barrett, John; Benson, Bradford A.; Bintley, Dan; Blackburn, Lindy; Blundell, Raymond; Boland, Wilfred; Bouman, Katherine L.; Bower, Geoffrey C.; Boyce, Hope; Bremer, Michael; Brinkerink, Christiaan D.; Brissenden, Roger; Britzen, Silke; Broderick, Avery E.; Broguiere, Dominique; Bronzwaer, Thomas; Byun, Do-Young; Carlstrom, John E.; Chael, Andrew; Chan, Chi-kwan; Chatterjee, Shami; Chatterjee, Koushik; Chen, Ming-Tang; Chen, Yongjun; Chesler, Paul M.; Cho, Ilje; Christian, Pierre; Conway, John E.; Cordes, James M.; Crawford, Thomas M.; Crew, Geoffrey B.; Cruz-Osorio, Alejandro; Cui, Yuzhu; Davelaar, Jordy; De Laurentis, Mariafelicia; Deane, Roger; Dempsey, Jessica; Desvignes, Gregory; Dexter, Jason; Doeleman, Sheperd S.; Eatough, Ralph P.; Falcke, Heino; Farah, Joseph; Fish, Vincent L.; Fomalont, Ed; Ford, H. Alyson; Fraga-Encinas, Raquel; Friberg, Per; Fromm, Christian M.; Fuentes, Antonio; Galison, Peter; Gammie, Charles F.; García, Roberto; Gelles, Zachary; Gentaz, Olivier; Georgiev, Boris; Goddi, Ciriaco; Gold, Roman; Gómez, José L.; Gómez-Ruiz, Arturo I.; Gu, Minfeng; Gurwell, Mark; Hada, Kazuhiro; Haggard, Daryl; Hecht, Michael H.; Hesper, Ronald; Himwich, Elizabeth; Ho, Luis C.; Ho, Paul; Honma, Mareki; Huang, Chih-Wei L.; Huang, Lei; Hughes, David H.; Ikeda, Shiro; Inoue, Makoto; Issaoun, Sara; James, David J.; Jannuzi, Buell T.; Janssen, Michael; Jeter, Britton; Jiang, Wu; Jimenez-Rosales, Alejandra; Johnson, Michael D.; Jorstad, Svetlana; Jung, Taehyun; Karami, Mansour; Karuppusamy, Ramesh; Kawashima, Tomohisa; Keating, Garrett K.; Kettenis, Mark; Kim, Dong-Jin; Kim, Jae-Young; Kim, Jongsoo; Kim, Junhan; Kino, Motoki; Koay, Jun Yi; Kofuji, Yutaro; Koch, Patrick M.; Koyama, Shoko; Kramer, Michael; Kramer, Carsten; Krichbaum, Thomas P.; Kuo, Cheng-Yu; Lauer, Tod R.; Lee, Sang-Sung; Levis, Aviad; Li, Yan-Rong; Li, Zhiyuan; Lindqvist, Michael; Lico, Rocco; Lindahl, Greg; Liu, Jun; Liu, Kuo; Liuzzo, Elisabetta; Lo, Wen-Ping; Lobanov, Andrei P.; Loinard, Laurent; Lonsdale, Colin; Lu, Ru-Sen; MacDonald, Nicholas R.; Mao, Jirong; Marchili, Nicola; Markoff, Sera; Marrone, Daniel P.; Marscher, Alan P.; Martí-Vidal, Iván; Matsushita, Satoki; Matthews, Lynn D.; Medeiros, Lia; Menten, Karl M.; Mizuno, Izumi; Mizuno, Yosuke; Moran, James M.; Moriyama, Kotaro; Moscibrodzka, Monika; Müller, Cornelia; Musoke, Gibwa; Mus Mejías, Alejandro; Michalik, Daniel; Nadolski, Andrew; Nagai, Hiroshi; Nagar, Neil M.; Nakamura, Masanori; Narayan, Ramesh; Narayanan, Gopal; Natarajan, Iniyan; Nathanail, Antonios; Neilsen, Joey; Neri, Roberto; Ni, Chunchong; Noutsos, Aristeidis; Nowak, Michael A.; Okino, Hiroki; Olivares, Héctor; Ortiz-León, Gisela N.; Oyama, Tomoaki; Özel, Feryal; Palumbo, Daniel C. M.; Park, Jongho; Patel, Nimesh; Pen, Ue-Li; Pesce, Dominic W.; Piétu, Vincent; Plambeck, Richard; PopStefanija, Aleksandar; Porth, Oliver; Pötzl, Felix M.; Prather, Ben; Preciado-López, Jorge A.; Psaltis, Dimitrios; Pu, Hung-Yi; Ramakrishnan, Venkatessh; Rao, Ramprasad; Rawlings, Mark G.; Raymond, Alexander W.; Rezzolla, Luciano; Ricarte, Angelo; Ripperda, Bart; Roelofs, Freek; Rogers, Alan; Ros, Eduardo; Rose, Mel; Roshanineshat, Arash; Rottmann, Helge; Roy, Alan L.; Ruszczyk, Chet; Rygl, Kazi L. J.; Sánchez, Salvador; Sánchez-Arguelles, David; Sasada, Mahito; Savolainen, Tuomas; Schloerb, F. Peter; Schuster, Karl-Friedrich; Shao, Lijing; Shen, Zhiqiang; Small, Des; Sohn, Bong Won; SooHoo, Jason; Sun, He; Tazaki, Fumie; Tetarenko, Alexandra J.; Tiede, Paul; Tilanus, Remo P. J.; Titus, Michael; Toma, Kenji; Torne, Pablo; Trent, Tyler; Traianou, Efthalia; Trippe, Sascha; van Bemmel, Ilse; van Langevelde, Huib Jan; van Rossum, Daniel R.; Wagner, Jan; Ward-Thompson, Derek; Wardle, John; Weintroub, Jonathan; Wex, Norbert; Wharton, Robert; Wielgus, Maciek; Wong, George N.; Wu, Qingwen; Yoon, Doosoo; Young, André; Young, Ken; Younsi, Ziri; Yuan, Feng; Yuan, Ye-Fei; Zensus, J. Anton; Zhao, Guang-Yao; Zhao, Shan-Shan
Abstract: Event Horizon Telescope (EHT) observations at 230 GHz have now imaged polarized emission around the supermassive black hole in M87 on event-horizon scales. This polarized synchrotron radiation probes the structure of magnetic fields and the plasma properties near the black hole. Here we compare the resolved polarization structure observed by the EHT, along with simultaneous unresolved observations with the Atacama Large Millimeter/submillimeter Array, to expectations from theoretical models. The low fractional linear polarization in the resolved image suggests that the polarization is scrambled on scales smaller than the EHT beam, which we attribute to Faraday rotation internal to the emission region. We estimate the average density n_e ∼ 10^4-7 cm^-3, magnetic field strength B ∼ 1-30 G, and electron temperature T_e ∼ (1-12) × 10¹⁰ K of the radiating plasma in a simple one-zone emission model. We show that the net azimuthal linear polarization pattern may result from organized, poloidal magnetic fields in the emission region. In a quantitative comparison with a large library of simulated polarimetric images from general relativistic magnetohydrodynamic (GRMHD) simulations, we identify a subset of physical models that can explain critical features of the polarimetric EHT observations while producing a relativistic jet of sufficient power. The consistent GRMHD models are all of magnetically arrested accretion disks, where near-horizon magnetic fields are dynamically important. We use the models to infer a mass accretion rate onto the black hole in M87 of (3-20) × 10^-4 M_⊙ yr^-1.

ID: 159443
Type: article
Authors: Raymond, Alexander W.; Palumbo, Daniel; Paine, Scott N.; Blackburn, Lindy; Córdova Rosado, Rodrigo; Doeleman, Sheperd S.; Farah, Joseph R.; Johnson, Michael D.; Roelofs, Freek; Tilanus, Remo P. J.; Weintroub, Jonathan
Abstract: The Event Horizon Telescope (EHT) is a very long-baseline interferometer built to image supermassive black holes on event-horizon scales. In this paper, we investigate candidate sites for an expanded EHT array with improved imaging capabilities. We use historical meteorology and radiative transfer analysis to evaluate site performance. Most of the existing sites in the EHT array have median zenith opacity less than 0.2 at 230 GHz during the March/April observing season. Seven of the existing EHT sites have 345 GHz opacity less than 0.5 during observing months. Out of more than 40 candidate new locations analyzed, approximately half have 230 GHz opacity comparable to the existing EHT sites, and at least 17 of the candidate sites would be comparably good for 345 GHz observing. A group of new sites with favorable transmittance and geographic placement leads to greatly enhanced imaging and science on horizon scales.

ID: 159444
Type: article
Authors: Xu, Y.; Bian, S. B.; Reid, M. J.; Li, J. J.; Menten, K. M.; Dame, T. M.; Zhang, B.; Brunthaler, A.; Wu, Y. W.; Moscadelli, L.; Wu, G.; Zheng, X. W.
Abstract: We have measured trigonometric parallaxes for four H₂O masers associated with distant massive young stars in the inner regions of the Galaxy using the Very Long Baseline Array as part of the BeSSeL Survey. G026.50 + 0.28 is located at the near end of the Galactic bar, perhaps at the origin of the Norma spiral arm. G020.77−0.05 is in the Galactic Center region and is likely associated with a far-side extension of the Scutum arm. G019.60−0.23 and G020.08−0.13 are likely associated and lie well past the Galactic Center. These sources appear to be in the Sagittarius spiral arm, but an association with the Perseus arm cannot be ruled out.

ID: 159445
Type: article
Authors: Hilton, M.; Sifón, C.; Naess, S.; Madhavacheril, M.; Oguri, M.; Rozo, E.; Rykoff, E.; Abbott, T. M. C.; Adhikari, S.; Aguena, M.; Aiola, S.; Allam, S.; Amodeo, S.; Amon, A.; Annis, J.; Ansarinejad, B.; Aros-Bunster, C.; Austermann, J. E.; Avila, S.; Bacon, D.; Battaglia, N.; Beall, J. A.; Becker, D. T.; Bernstein, G. M.; Bertin, E.; Bhandarkar, T.; Bhargava, S.; Bond, J. R.; Brooks, D.; Burke, D. L.; Calabrese, E.; Carrasco Kind, M.; Carretero, J.; Choi, S. K.; Choi, A.; Conselice, C.; da Costa, L. N.; Costanzi, M.; Crichton, D.; Crowley, K. T.; Dünner, R.; Denison, E. V.; Devlin, M. J.; Dicker, S. R.; Diehl, H. T.; Dietrich, J. P.; Doel, P.; Duff, S. M.; Duivenvoorden, A. J.; Dunkley, J.; Everett, S.; Ferraro, S.; Ferrero, I.; Ferté, A.; Flaugher, B.; Frieman, J.; Gallardo, P. A.; García-Bellido, J.; Gaztanaga, E.; Gerdes, D. W.; Giles, P.; Golec, J. E.; Gralla, M. B.; Grandis, S.; Gruen, D.; Gruendl, R. A.; Gschwend, J.; Gutierrez, G.; Han, D.; Hartley, W. G.; Hasselfield, M.; Hill, J. C.; Hilton, G. C.; Hincks, A. D.; Hinton, S. R.; Ho, S. -P P.; Honscheid, K.; Hoyle, B.; Hubmayr, J.; Huffenberger, K. M.; Hughes, J. P.; Jaelani, A. T.; Jain, B.; James, David J.; Jeltema, T.; Kent, S.; Knowles, K.; Koopman, B. J.; Kuehn, K.; Lahav, O.; Lima, M.; Lin, Y. -T; Lokken, M.; Loubser, S. I.; MacCrann, N.; Maia, M. A. G.; Marriage, T. A.; Martin, J.; McMahon, J.; Melchior, P.; Menanteau, F.; Miquel, R.; Miyatake, H.; Moodley, K.; Morgan, R.; Mroczkowski, T.; Nati, F.; Newburgh, L. B.; Niemack, M. D.; Nishizawa, A. J.; Ogando, R. L. C.; Orlowski-Scherer, J.; Page, L. A.; Palmese, A.; Partridge, B.; Paz-Chinchón, F.; Phakathi, P.; Plazas, A. A.; Robertson, N. C.; Romer, A. K.; Carnero Rosell, A.; Salatino, M.; Sanchez, E.; Schaan, E.; Schillaci, A.; Sehgal, N.; Serrano, S.; Shin, T.; Simon, S. M.; Smith, M.; Soares-Santos, M.; Spergel, D. N.; Staggs, S. T.; Storer, E. R.; Suchyta, E.; Swanson, M. E. C.; Tarle, G.; Thomas, D.; To, C.; Trac, H.; Ullom, J. N.; Vale, L. R.; Van Lanen, J.; Vavagiakis, E. M.; De Vicente, J.; Wilkinson, R. D.; Wollack, E. J.; Xu, Z.; Zhang, Y.
Abstract: We present a catalog of 4195 optically confirmed Sunyaev–Zel'dovich (SZ) selected galaxy clusters detected with signal-to-noise ratio >4 in 13,211 deg² of sky surveyed by the Atacama Cosmology Telescope (ACT). Cluster candidates were selected by applying a multifrequency matched filter to 98 and 150 GHz maps constructed from ACT observations obtained from 2008 to 2018 and confirmed using deep, wide-area optical surveys. The clusters span the redshift range 0.04 of sky surveyed by the Atacama Cosmology Telescope (ACT). Cluster candidates were selected by applying a multifrequency matched filter to 98 and 150 GHz maps constructed from ACT observations obtained from 2008 to 2018 and confirmed using deep, wide-area optical surveys. The clusters span the redshift range 0.04 1 clusters, and a total of 868 systems are new discoveries. Assuming an SZ signal versus mass-scaling relation calibrated from X-ray observations, the sample has a 90% completeness mass limit of M _500c > 3.8 × 10¹⁴ M _⊙, evaluated at z = 0.5, for clusters detected at signal-to-noise ratio >5 in maps filtered at an angular scale of 2.′4. The survey has a large overlap with deep optical weak-lensing surveys that are being used to calibrate the SZ signal mass-scaling relation, such as the Dark Energy Survey (4566 deg²), the Hyper Suprime-Cam Subaru Strategic Program (469 deg²), and the Kilo Degree Survey (825 deg²). We highlight some noteworthy objects in the sample, including potentially projected systems, clusters with strong lensing features, clusters with active central galaxies or star formation, and systems of multiple clusters that may be physically associated. The cluster catalog will be a useful resource for future cosmological analyses and studying the evolution of the intracluster medium and galaxies in massive clusters over the past 10 Gyr.

ID: 159315
Type: article
Authors: Flor-Torres, L. M.; Coziol, R.; Schröder, K. -P; Jack, D.; Schmitt, J. H. M. M.; Blanco-Cuaresma, Sergi
Abstract: In search for a connection between the formation of stars and the formation of planets, a new semi-automatic spectral analysis method using iSpec was developed for the TIGRE telescope installed in Guanajuato, Mexico. TIGRE is a 1.2m robotic telescope, equipped with an Echelle spectrograph (HEROS), with a resolution R ≃ 20000. iSpec is a synthetic spectral fitting program for stars that allows to determine in an homogeneous way their fundamental parameters: effective temperature, T_eff, surface gravity, log g, metallicities, [M/H] and [Fe/H], and rotational velocity, V sin i. In this first article we test our method by analysing the spectra of 46 stars, hosts of exoplanets, obtained with the TIGRE.