Publication Search Results

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: 158735
Type: article
Authors: Cruz-González, I.; Gómez-Ruiz, A. I.; Caldú-Primo, A.; Benítez, E.; Rodríguez-Espinosa, J. M.; Krongold, Y.; Aretxaga, I.; Snell, R.; González-Martin, O.; Negrete, C. A.; Narayanan, G.; Hughes, D. H.; Yun, M. S.; Fazio, Giovanni G.; Chavushyan, V.; Hiriart, D.; Jiménez-Bailón, E.; Herrera-Endoqui, M.; Martínez-Paredes, M.; González, J. J.
Abstract: As part of the Early Science Large Millimeter Telescope projects, we report the detection of nine double-peaked molecular lines, produced by a rotating molecular torus, in the ultraluminous infrared galaxies (ULIRG) - Compton-thick active galactic nuclei (AGN) galaxy UGC 5101. The double-peaked lines we report correspond to molecular transitions of HCN, HCO⁺, HNC, N₂H⁺, CS, C¹⁸O, ¹³CO, and two CN lines; plus the detection of C₂H that is a blend of six lines. The redshift search receiver spectra covers the 73-113 GHz frequency window. Low- and high-density gas tracers of the torus have different implied rotational velocities, with a rotational velocity of 149 ± 3 km s^-1 for the low-density ones (C¹⁸O, ¹³CO) and 174 ± 3 km s^-1 for high-density tracers (HCN, HCO⁺, HNC, N₂H⁺, CS, and CN). In UGC 5101, we find that the ratio of integrated intensities of HCN to ¹³CO to be unusually large, probably indicating that the gas in the torus is very dense. Both the column densities and abundances are consistent with values found in AGN, starburst, and ULIRG galaxies. The observed abundance ratios cannot discriminate between X-ray and UV-field-dominated regions.

ID: 154285
Type: article
Authors: Barro, Guillermo; Pérez-González, Pablo G.; Cava, Antonio; Brammer, Gabriel; Pandya, Viraj; Eliche Moral, Carmen; Esquej, Pilar; Domínguez-Sánchez, Helena; Alcalde Pampliega, Belen; Guo, Yicheng; Koekemoer, Anton M.; Trump, Jonathan R.; Ashby, Matthew L. N.; Cardiel, Nicolas; Castellano, Marco; Conselice, Christopher J.; Dickinson, Mark E.; Dolch, Timothy; Donley, Jennifer L.; Espino Briones, Néstor; Faber, Sandra M.; Fazio, Giovanni G.; Ferguson, Henry; Finkelstein, Steve; Fontana, Adriano; Galametz, Audrey; Gardner, Jonathan P.; Gawiser, Eric; Giavalisco, Mauro; Grazian, Andrea; Grogin, Norman A.; Hathi, Nimish P.; Hemmati, Shoubaneh; Hernán-Caballero, Antonio; Kocevski, Dale; Koo, David C.; Kodra, Dritan; Lee, Kyoung-Soo; Lin, Lihwai; Lucas, Ray A.; Mobasher, Bahram; McGrath, Elizabeth J.; Nandra, Kirpal; Nayyeri, Hooshang; Newman, Jeffrey A.; Pforr, Janine; Peth, Michael; Rafelski, Marc; Rodríguez-Munoz, Lucia; Salvato, Mara; Stefanon, Mauro; van der Wel, Arjen; Willner, Steven P.; Wiklind, Tommy; Wuyts, Stijn
Abstract: We present a WFC3 F160W (H-band) selected catalog in the CANDELS/GOODS-N field containing photometry from the ultraviolet (UV) to the far- infrared (IR), photometric redshifts, and stellar parameters derived from the analysis of the multiwavelength data. The catalog contains 35,445 sources over the 171 arcmin² of the CANDELS F160W mosaic. The 5σ detection limits (within an aperture of radius 0.″17) of the mosaic range between H = 27.8, 28.2, and 28.7 in the wide, intermediate, and deep regions, which span approximately 50%, 15%, and 35% of the total area. The multiwavelength photometry includes broadband data from the UV (U band from KPNO and LBC), optical (HST/ACS F435W, F606W, F775W, F814W, and F850LP), near-to-mid IR (HST/WFC3 F105W, F125W, F140W, and F160W; Subaru/MOIRCS Ks; CFHT/Megacam K; and Spitzer/IRAC 3.6, 4.5, 5.8, and 8.0 μm), and far-IR (Spitzer/MIPS 24 μm, HERSCHEL/PACS 100 and 160 μm, SPIRE 250, 350 and 500 μm) observations. In addition, the catalog also includes optical medium-band data (R ̃ 50) in 25 consecutive bands, λ = 500-950 nm, from the SHARDS survey and WFC3 IR spectroscopic observations with the G102 and G141 grisms (R ̃ 210 and 130). The use of higher spectral resolution data to estimate photometric redshifts provides very high, and nearly uniform, precision from z = 0-2.5. The comparison to 1485 good-quality spectroscopic redshifts up to z ̃ 3 yields ∆z/(1 + z _spec) = 0.0032 and an outlier fraction of η = 4.3%. In addition to the multiband photometry, we release value- added catalogs with emission-line fluxes, stellar masses, dust attenuations, UV- and IR-based star formation rates, and rest-frame colors.

ID: 150489
Type: article
Authors: Boyce, H.; Haggard, D.; Witzel, G.; Willner, Steven P.; Neilsen, J.; Hora, Joseph L.; Markoff, S.; Ponti, G.; Baganoff, F.; Becklin, E. E.; Fazio, Giovanni G.; Lowrance, P.; Morris, M. R.; Smith, H. A.
Abstract: Emission from Saggitarius A* is highly variable at both X-ray and infrared (IR) wavelengths. Observations over the last ∼20 yr have revealed X-ray flares that rise above a quiescent thermal background about once per day, while faint X-ray flares from Sgr A* are undetectable below the constant thermal emission. In contrast, the IR emission of Sgr A* is observed to be continuously variable. Recently, simultaneous observations have indicated a rise in IR flux density around the same time as every distinct X-ray flare, while the opposite is not always true (peaks in the IR emission may not be coincident with an X-ray flare). Characterizing the behavior of these simultaneous X-ray/IR events and measuring any time lag between them can constrain models of Sgr A*'s accretion flow and the flare emission mechanism. Using 100+ hours of data from a coordinated campaign between the Spitzer Space Telescope and the Chandra X-ray Observatory, we present results of the longest simultaneous IR and X-ray observations of Sgr A* taken to date. The cross-correlation between the IR and X-ray light curves in this unprecedented data set, which includes four modest X-ray/IR flares, indicates that flaring in the X-ray may lead the IR by approximately 10–20 min with 68% confidence. However, the 99.7% confidence interval on the time-lag also includes zero, i.e., the flaring remains statistically consistent with simultaneity. Long-duration and simultaneous multi-wavelength observations of additional bright flares will improve our ability to constrain the flare timing characteristics and emission mechanisms, and must be a priority for Galactic Center observing campaigns.

ID: 155240
Type: article
Authors: Cowley, William I.; Caputi, Karina I.; Deshmukh, Smaran; Ashby, Matthew L. N.; Fazio, Giovanni G.; Le Fèvre, Olivier; Fynbo, Johan P. U.; Ilbert, Oliver; Milvang-Jensen, Bo
Abstract: In this work, we use measurements of galaxy stellar mass and two-point angular correlation functions to constrain the stellar-to-halo mass ratios (SHMRs) of passive and star-forming galaxies at z ̃ 2-3, as identified in the Spitzer Matching Survey of the UltraVISTA ultra-deep Stripes. We adopt a sophisticated halo modeling approach to statistically divide our two populations into central and satellite galaxies. For central galaxies, we find that the normalization of the SHMR is greater for our passive population. Through the modeling of Λ cold dark matter halo mass accretion histories, we show that this can only arise if the conversion of baryons into stars was more efficient at higher redshifts and additionally that passive galaxies can be plausibly explained as residing in halos with the highest formation redshifts (i.e., those with the lowest accretion rates) at a given halo mass. At a fixed stellar mass, satellite galaxies occupy host halos with a greater mass than central galaxies, and we find further that the fraction of passive galaxies that are satellites is higher than for the combined population. This, and our derived satellite quenching timescales, combined with earlier estimates from the literature, support dynamical/environmental mechanisms as the dominant process for satellite quenching at z ≲ 3.

ID: 149176
Type: article
Authors: Fazio, G. G.; Hora, J. L.; Witzel, G.; Willner, S. P.; Ashby, M. L. N.; Baganoff, F.; Becklin, E.; Carey, S.; Haggard, D.; Gammie, C.; Ghez, A.; Gurwell, M. A.; Ingalls, J.; Marrone, D.; Morris, M. R.; Smith, H. A.
Abstract: Sgr A*, the supermassive black hole (SMBH) at the center of our Milky Way Galaxy, is known to be a variable source of X-ray, near-infrared (NIR), and submillimeter radiation and therefore a prime candidate to study the electromagnetic radiation generated by mass accretion flow onto a black hole and/or a related jet. Disentangling the power source and emission mechanisms of this variability is a central challenge to our understanding of accretion flows around SMBHs. Simultaneous multiwavelength observations of the flux variations and their time correlations can play an important role in obtaining a better understanding of possible emission mechanisms and their origin. This paper presents observations of two flares that both apparently violate the previously established patterns in the relative timing of submillimeter/NIR/X-ray flares from Sgr A*. One of these events provides the first evidence of coeval structure between NIR and submillimeter flux increases, while the second event is the first example of the sequence of submillimeter/X-ray/NIR flux increases all occurring within ∼1 hr. Each of these two events appears to upend assumptions that have been the basis of some analytic models of flaring in Sgr A*. However, it cannot be ruled out that these events, even though unusual, were just coincidental. These observations demonstrate that we do not fully understand the origin of the multiwavelength variability of Sgr A* and show that there is a continued and important need for long-term, coordinated, and precise multiwavelength observations of Sgr A* to characterize the full range of variability behavior.

ID: 150499
Type: article
Authors: Hsu, Li-Ting; Lin, Lihwai; Dickinson, Mark; Yan, Haojing; Bau-Ching, Hsieh; Wang, Wei-Hao; Lee, Chien-Hsiu; Yan, Chi-Hung; Scott, Douglas; Willner, Steven P.; Ouchi, Masami; Ashby, Matthew L. N.; Chen, Yi-Wen; Daddi, Emanuele; Elbaz, David; Fazio, Giovanni G.; Foucaud, Sebastien; Huang, Jiasheng; Koo, David C.; Morrison, Glenn; Owen, Frazer; Pannella, Maurilio; Pope, Alexendra; Simard, Luc; Wang, Shiang-Yu
Abstract: We present deep J- and H-band images in the extended Great Observatories Origins Deep Survey-North field covering an area of 0.22 deg². The observations were taken using WIRCam on the 3.6 m Canada–France–Hawaii Telescope. Together with the reprocessed K _s-band image, the 5σ limiting AB magnitudes (in 2″ diameter apertures) are 24.7, 24.2, and 24.4 AB mag in the J, H, and K _s bands, respectively. We also release a multiband photometry and photometric redshift catalog containing 93,598 sources. For non-X-ray sources, we obtained a photometric redshift accuracy σ _NMAD = 0.036 with an outlier fraction η = 7.3%. For X-ray sources, which are mainly active galactic nuclei (AGNs), we cross-matched our catalog with the updated 2M-CDFN X-ray catalog from Xue et al. and found that 658 out of 683 X-ray sources have counterparts. GALEX UV data are included in the photometric redshift computation for the X-ray sources to give σ _NMAD = 0.040 with η = 10.5%. Our approach yields more accurate photometric redshift estimates compared to previous works in this field. In particular, by adopting AGN–galaxy hybrid templates, our approach delivers photometric redshifts for the X-ray counterparts with fewer outliers compared to the 3D-Hubble Space Telescope catalog, which fit these sources with galaxy-only templates.

ID: 150444
Type: article
Authors: Mahajan, Smriti; Ashby, Matthew L. N.; Willner, Steven P.; Barmby, P.; Fazio, Giovanni G.; Maragkoudakis, A.; Raychaudhury, S.; Zezas, A.
Abstract: We present multiwavelength global star formation rate (SFR) estimates for 326 galaxies from the Star Formation Reference Survey in order to determine the mutual scatter and range of validity of different indicators. The widely used empirical SFR recipes based on 1.4 GHz continuum, 8.0 μm polycyclic aromatic hydrocarbons (PAHs), and a combination of far-infrared (FIR) plus ultraviolet (UV) emission are mutually consistent with scatter of ≲0.3 dex. The scatter is even smaller, ≲0.24 dex, in the intermediate luminosity range 9.35 × 10⁹ L_⊙ or with implied far-UV extinction <1 mag, the UV spectral slope gives extinction corrections with 0.22 dex uncertainty.

ID: 150533
Type: article
Authors: U, Vivian; Medling, Anne M.; Inami, Hanae; Armus, Lee; Díaz-Santos, Tanio; Charmandaris, Vassilis; Howell, Justin; Stierwalt, Sabrina; Privon, George C.; Linden, Sean T.; Sanders, David B.; Max, Claire E.; Evans, Aaron S.; Barcos-Muñoz, Loreto; Chiang, Charleston W. K.; Appleton, Phil; Canalizo, Gabriela; Fazio, Giovanni; Iwasawa, Kazushi; Larson, Kirsten; Mazzarella, Joseph; Murphy, Eric; Rich, Jeffrey; Surace, Jason
Abstract: The role of feedback in triggering or quenching star formation and hence driving galaxy evolution can be directly studied with high-resolution integral field observations. The manifestation of feedback in shocks is particularly important to examine in galaxy mergers, where violent interactions of gas take place in the interstellar medium during the course of the galactic collision. As part of our effort to systematically study the local population of luminous infrared galaxies within the Great Observatories All-Sky LIRG Survey, we undertook the Keck OSIRIS AO LIRG Analysis observing campaign to study the gas dynamics in the inner kiloparsec regions of these systems at spatial scales of a few tens of pc. With high-resolution near-infrared adaptive optics–assisted integral field observations taken with OSIRIS on the Keck Telescopes, we employ near-infrared diagnostics such as Brγ and the rovibrationally excited H₂ lines to quantify the nuclear star formation rate and identify feedback associated with shocked molecular gas seen in 21 nearby luminous infrared galaxies. Shocked molecular gas is preferentially found in the ultraluminous infrared systems but may also be triggered at a lower-luminosity, earlier merging stage. On circumnuclear scales, AGNs have a strong effect on heating the surrounding molecular gas, though their coupling is not simply driven by AGN strength but rather is complicated by orientation, dust shielding, density, and other factors. We find that nuclear star formation correlates with merger class and diminishing projected nuclear separations. These trends are largely consistent with the picture of merger-induced starbursts in the center of galaxy mergers.

ID: 154696
Type: article
Authors: Zhou, Rongpu; Cooper, Michael C.; Newman, Jeffrey A.; Ashby, Matthew L. N.; Aird, James; Conselice, Christopher J.; Davis, Marc; Dutton, Aaron A.; Faber, S. M.; Fang, Jerome J.; Fazio, Giovanni G.; Guhathakurta, Puragra; Kocevski, Dale; Koo, David C.; Nandra, Kirpal; Phillips, Andrew C.; Rosario, David J.; Schlafly, Edward F.; Trump, Jonathan R.; Weiner, Benjamin; Willmer, Christopher N. A.; Yan, Renbin
Abstract: We present catalogues of calibrated photometry and spectroscopic redshifts in the Extended Groth Strip, intended for studies of photometric redshifts (photo-z's). The data includes ugriz photometry from Canada-France-Hawaii Telescope Legacy Survey (CFHTLS) and Y-band photometry from the Subaru Suprime camera, as well as spectroscopic redshifts from the DEEP2, DEEP3, and 3D-HST surveys. These catalogues incorporate corrections to produce effectively matched-aperture photometry across all bands, based upon object size information available in the catalogue and Moffat profile point spread function fits. We test this catalogue with a simple machine learning-based photometric redshift algorithm based upon Random Forest regression, and find that the corrected aperture photometry leads to significant improvement in photo-z accuracy compared to the original SEXTRACTOR catalogues from CFHTLS and Subaru. The deep ugrizY photometry and spectroscopic redshifts are well suited for empirical tests of photometric redshift algorithms for LSST. The resulting catalogues are publicly available at http://d-scholarship.pitt.edu/36064/. We include a basic summary of the strategy of the DEEP3 Galaxy Redshift Survey to accompany the recent public release of DEEP3 data.

ID: 145753
Type: article
Authors: Cowley, William I.; Caputi, Karina I.; Deshmukh, Smaran; Ashby, Matthew L. N.; Fazio, Giovanni G.; Le Fèvre, Olivier; Fynbo, Johan P. U.; Ilbert, Olivier; McCracken, Henry J.; Milvang-Jensen, Bo; Somerville, Rachel S.
Abstract: The Spitzer Matching Survey of the UltraVISTA ultra-deep Stripes (SMUVS) provides unparalleled depth at 3.6 and 4.5 mum over ~0.66 deg² of the COSMOS field, allowing precise photometric determinations of redshift and stellar mass. From this unique data set we can connect galaxy samples, selected by stellar mass, to their host dark matter halos for 1.5 of the COSMOS field, allowing precise photometric determinations of redshift and stellar mass. From this unique data set we can connect galaxy samples, selected by stellar mass, to their host dark matter halos for 1.5 of the COSMOS field, allowing precise photometric determinations of redshift and stellar mass. From this unique data set we can connect galaxy samples, selected by stellar mass, to their host dark matter halos for 1.5^{12.5_-0.08^+0.10} {M}_o at z~ 2.5. This peak halo mass is here inferred for the first time from stellar mass-selected clustering measurements at z&gsim; 2, and it implies a mild evolution of this quantity for z&lsim; 3, consistent with constraints from abundance-matching techniques.

ID: 147467
Type: article
Authors: Hayward, Christopher C.; Chapman, Scott C.; Steidel, Charles C.; Golob, Anneya; Casey, Caitlin M.; Smith, Daniel J. B.; Zitrin, Adi; Blain, Andrew W.; Bremer, Malcolm N.; Chen, Chian-Chou; Coppin, Kristen E. K.; Farrah, Duncan; Ibar, Eduardo; Michalowski, Michal J.; Sawicki, Marcin; Scott, Douglas; van der Werf, Paul; Fazio, Giovanni G.; Geach, James E.; Gurwell, Mark; Petitpas, Glen; Wilner, David J.
Abstract: Interferometric observations have demonstrated that a significant fraction of single-dish submillimetre (submm) sources are blends of multiple submm galaxies (SMGs), but the nature of this multiplicity, i.e. whether the galaxies are physically associated or chance projections, has not been determined. We performed spectroscopy of 11 SMGs in six multicomponent submm sources, obtaining spectroscopic redshifts for nine of them. For an additional two component SMGs, we detected continuum emission but no obvious features. We supplement our observed sources with four single-dish submm sources from the literature. This sample allows us to statistically constrain the physical nature of single-dish submm source multiplicity for the first time. In three (3/7, { or} 43^{+39 }_{ -33} {per cent at 95 {per cent} confidence}) of the single-dish sources for which the nature of the blending is unambiguous, the components for which spectroscopic redshifts are available are physically associated, whereas 4/7 (57^{+33 }_{ -39} per cent) have at least one unassociated component. When components whose spectra exhibit continuum but no features and for which the photometric redshift is significantly different from the spectroscopic redshift of the other component are also considered, 6/9 (67^{+26 }_{ -37} per cent) of the single-dish sources are comprised of at least one unassociated component SMG. The nature of the multiplicity of one single-dish source is ambiguous. We conclude that physically associated systems and chance projections both contribute to the multicomponent single-dish submm source population. This result contradicts the conventional wisdom that bright submm sources are solely a result of merger-induced starbursts, as blending of unassociated galaxies is also important.

ID: 149376
Type: article
Authors: Hora, Joseph L.; Siraj, Amir; Mommert, Michael; McNeill, Andrew; Trilling, David E.; Gustafsson, Annika; Smith, Howard A.; Fazio, Giovanni G.; Chesley, Steven; Emery, Joshua P.; Harris, Alan; Mueller, Michael
Abstract: We present light curves and derive periods and amplitudes for a subset of 38 near-Earth objects (NEOs) observed at 4.5 μm with the IRAC camera on the the Spitzer Space Telescope, many of them having no previously reported rotation periods. This subset was chosen from about 1800 IRAC NEO observations as having obvious periodicity and significant amplitude. For objects where the period observed did not sample the full rotational period, we derived lower limits to these parameters based on sinusoidal fits. Light curve durations ranged from 42 to 544 minutes, with derived periods from 16 to 270 minutes. We discuss the effects of light curve variations on the thermal modeling used to derive diameters and albedos from Spitzer photometry. We find that both diameters and albedos derived from the light curve maxima and minima agree with our previously published results, even for extreme objects, showing the conservative nature of the thermal model uncertainties. We also evaluate the NEO rotation rates, sizes, and their cohesive strengths.

ID: 150221
Type: article
Authors: Trilling, David E.; Mommert, Michael; Hora, Joseph L.; Farnocchia, Davide; Chodas, Paul; Giorgini, Jon; Smith, Howard A.; Carey, Sean; Lisse, Carey M.; Werner, Michael; McNeill, Andrew; Chesley, Steven R.; Emery, Joshua P.; Fazio, Giovanni G.; Fernandez, Yanga R.; Harris, Alan; Marengo, Massimo; Mueller, Michael; Roegge, Alissa; Smith, Nathan; Weaver, H. A.; Meech, Karen; Micheli, Marco
Abstract: 1I/‘Oumuamua is the first confirmed interstellar body in our solar system. Here we report on observations of ‘Oumuamua made with the Spitzer Space Telescope on 2017 November 21–22 (UT). We integrated for 30.2 hr at 4.5 μm (IRAC channel 2). We did not detect the object and place an upper limit on the flux of 0.3 μJy (3σ). This implies an effective spherical diameter less than [98, 140, 440] m and albedo greater than [0.2, 0.1, 0.01] under the assumption of low, middle, or high thermal beaming parameter η, respectively. With an aspect ratio for ‘Oumuamua of 6:1, these results correspond to dimensions of [240:40, 341:57, 1080:180] m, respectively. We place upper limits on the amount of dust, CO, and CO₂ coming from this object that are lower than previous results; we are unable to constrain the production of other gas species. Both our size and outgassing limits are important because ‘Oumuamua’s trajectory shows non-gravitational accelerations that are sensitive to size and mass and presumably caused by gas emission. We suggest that ‘Oumuamua may have experienced low-level post-perihelion volatile emission that produced a fresh, bright, icy mantle. This model is consistent with the expected η value and implied high-albedo value for this solution, but, given our strict limits on CO and CO₂, requires another gas species—probably H₂O—to explain the observed non-gravitational acceleration. Our results extend the mystery of ‘Oumuamua’s origin and evolution.

ID: 148995
Type: article
Authors: Witzel, G.; Martinez, G.; Hora, J.; Willner, S. P.; Morris, M. R.; Gammie, C.; Becklin, E. E.; Ashby, M. L. N.; Baganoff, F.; Carey, S.; Do, T.; Fazio, G. G.; Ghez, A.; Glaccum, W. J.; Haggard, D.; Herrero-Illana, R.; Ingalls, J.; Narayan, R.; Smith, H. A.
Abstract: Sagittarius A* (Sgr A*) is the variable radio, near-infrared (NIR), and X-ray source associated with accretion onto the Galactic center black hole. We present an analysis of the most comprehensive NIR variability data set of Sgr A* to date: eight 24 hr epochs of continuous monitoring of Sgr A* at 4.5 mum with the IRAC instrument on the Spitzer Space Telescope, 93 epochs of 2.18 mum data from Naos Conica at the Very Large Telescope, and 30 epochs of 2.12 mum data from the NIRC2 camera at the Keck Observatory, in total 94,929 measurements. A new approximate Bayesian computation method for fitting the first-order structure function extracts information beyond current fast Fourier transformation (FFT) methods of power spectral density (PSD) estimation. With a combined fit of the data of all three observatories, the characteristic coherence timescale of Sgr A* is {tau }_b={243}_-57⁺⁸² minutes (90% credible interval). The PSD has no detectable features on timescales down to 8.5 minutes (95% credible level), which is the ISCO orbital frequency for a dimensionless spin parameter a = 0.92. One light curve measured simultaneously at 2.12 and 4.5 mum during a low flux-density phase gave a spectral index alpha _s = 1.6 ± 0.1 ({F}_nu \propto {nu }^-{alpha _s}). This value implies that the Sgr A* NIR color becomes bluer during higher flux-density phases. The probability densities of flux densities of the combined data sets are best fit by log-normal distributions. Based on these distributions, the Sgr A* spectral energy distribution is consistent with synchrotron radiation from a non-thermal electron population from below 20 GHz through the NIR.

ID: 144818
Type: article
Authors: Caputi, K. I.; Deshmukh, S.; Ashby, M. L. N.; Cowley, W. I.; Bisigello, L.; Fazio, G. G.; Fynbo, J. P. U.; Le Fèvre, O.; Milvang-Jensen, B.; Ilbert, O.
Abstract: We study a large galaxy sample from the Spitzer Matching Survey of the UltraVISTA ultra-deep Stripes (SMUVS) to search for sources with enhanced 3.6 ? {{m}} fluxes indicative of strong H? emission at z=3.9{--}4.9. We find that the percentage of "H? excess" sources reaches 37%-40% for galaxies with stellar masses {{log}}₁₀({M}^* /{M}_? )? 9{--}10 and decreases to )? 9{--}10 and decreases to ₁₀({M}^* /{M}_? )~ 10.7. At higher stellar masses, however, the trend reverses, although this is likely due to active galactic nucleus contamination. We derive star formation rates (SFR) and specific SFR (sSFR) from the inferred H? equivalent widths of our "H? excess" galaxies. We show, for the first time, that the "H? excess" galaxies clearly have a bimodal distribution on the SFR-M* plane: they lie on the main sequence of star formation (with {{log}}₁₀({sSFR}/{{yr}}^-1))₁₀({sSFR}/{{yr}}^-1)> -7.60). The latter contains ~ 15 % of all the objects in our sample and accounts for > 50 % of the cosmic SFR density at z=3.9{--}4.9, for which we derive a robust lower limit of 0.066 {M}_? {{yr}}^-1 {{Mpc}}^-3. Finally, we identify an unusual > 50? overdensity of z=3.9{--}4.9 galaxies within a 0.20× 0.20 arcmin² region. We conclude that the SMUVS unique combination of area and depth at mid-IR wavelengths provides an unprecedented level of statistics and dynamic range that are fundamental to revealing new aspects of galaxy evolution in the young universe.

ID: 143268
Type: article
Authors: Stefanon, Mauro; Yan, Haojing; Mobasher, Bahram; Barro, Guillermo; Donley, Jennifer L.; Fontana, Adriano; Hemmati, Shoubaneh; Koekemoer, Anton M.; Lee, BoMee; Lee, Seong-Kook; Nayyeri, Hooshang; Peth, Michael; Pforr, Janine; Salvato, Mara; Wiklind, Tommy; Wuyts, Stijn; Ashby, Matthew L. N.; Castellano, Marco; Conselice, Christopher J.; Cooper, Michael C.; Cooray, Asantha R.; Dolch, Timothy; Ferguson, Henry; Galametz, Audrey; Giavalisco, Mauro; Guo, Yicheng; Willner, Steven P.; Dickinson, Mark E.; Faber, Sandra M.; Fazio, Giovanni G.; Gardner, Jonathan P.; Gawiser, Eric; Grazian, Andrea; Grogin, Norman A.; Kocevski, Dale; Koo, David C.; Lee, Kyoung-Soo; Lucas, Ray A.; McGrath, Elizabeth J.; Nandra, Kirpal; Newman, Jeffrey A.; van der Wel, Arjen
Abstract: We present a 0.4-8 ?m multi-wavelength photometric catalog in the Extended Groth Strip (EGS) field. This catalog is built on the Hubble Space Telescope (HST) WFC3 and ACS data from the Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey (CANDELS), and it incorporates the existing HST data from the All-wavelength Extended Groth strip International Survey (AEGIS) and the 3D-HST program. The catalog is based on detections in the F160W band reaching a depth of F160W = 26.62 AB (90% completeness, point sources). It includes the photometry for 41,457 objects over an area of ? 206 arcmin² in the following bands: HST/ACS F606W and F814W; HST WFC3 F125W, F140W, and F160W; Canada-France-Hawaii Telescope (CFHT)/Megacam u*, g^\prime , r^\prime , i^\prime and z^\prime ; CFHT/WIRCAM J, H, and K _S; Mayall/NEWFIRM J1, J2, J3, H1, H2, and K; Spitzer IRAC 3.6, 4.5, 5.8, and 8.0 ?m. We are also releasing value-added catalogs that provide robust photometric redshifts and stellar mass measurements. The catalogs are publicly available through the CANDELS repository.

ID: 142775
Type: article
Authors: Ueda, Junko; Watanabe, Yoshimasa; Iono, Daisuke; Wilner, David J.; Fazio, Giovanni G.; Ohashi, Satoshi; Kawabe, Ryohei; Saito, Toshiki; Komugi, Shinya
Abstract: We present 1´´(⁺, CH₃OH, and HNCO-obtained towards NGC 4038, which is the northern galaxy of the mid-stage merger, Antennae galaxies, with the Atacama Large Millimeter/submillimeter Array. Three molecules (CN, CH₃OH, and HNCO) were detected for the first time in the nuclear region of NGC 4038. High-resolution mapping reveals a systematic difference in distributions of different molecular species and continuum emission. Active star-forming regions identified by the 3 mm and 850 ?m continuum emission are offset from the gas-rich region associated with the HCN (1-0) and CO (3-2) peaks. The CN (1-0)/HCN (1-0) line ratios are enhanced (CN/HCN ? 0.8-1.2) in the star-forming regions, suggesting that the regions are photon dominated. The large molecular gas mass (10⁸ M_?) within a 0{^''_.}6 (~60 pc) radius of the CO (3-2) peak and a high dense gas fraction (>20%) suggested by the HCN (1-0)/CO (3-2) line ratio may signify a future burst of intense star formation there. The shocked gas traced in the CH₃OH and HNCO emission indicates sub-kpc-scale molecular shocks. We suggest that the molecular shocks may be driven by collisions between inflowing gas and the central massive molecular complex.

ID: 142006
Type: article
Authors: Bouwens, R. J.; Oesch, P. A.; Labbé, I.; Illingworth, G. D.; Fazio, G. G.; Coe, D.; Holwerda, B.; Smit, R.; Stefanon, M.; van Dokkum, P. G.; Trenti, M.; Ashby, M. L. N.; Huang, J. -S; Spitler, L.; Straatman, C.; Bradley, L.; Magee, D.
Abstract: The deep, wide-area (˜800-900 arcmin²) near-infrared/WFC3/IR + Spitzer/IRAC observations over the CANDELS fields have been a remarkable resource for constraining the bright end of high-redshift UV luminosity functions. However, the lack of Hubble Space Telescope (HST) 1.05 µm observations over the CANDELS fields has made it difficult to identify z ˜ 9-10 sources robustly, since such data are needed to confirm the presence of an abrupt Lyman break at 1.2 µm. Here, we report on the successful identification of many such z ˜ 9-10 sources from a new HST program (z9-CANDELS) that targets the highest-probability z ˜ 9-10 galaxy candidates with observations at 1.05 µm, to search for a robust Lyman-break at 1.2 µm. The potential z ˜ 9-10 candidates were preselected from the full HST, Spitzer/IRAC S-CANDELS observations, and the deepest-available ground-based optical+near-infrared observations (CFHTLS-DEEP+HUGS+UltraVISTA+ZFOURGE). We identified 15 credible z ˜ 9-10 galaxies over the CANDELS fields. Nine of these galaxies lie at z ˜ 9 and five are new identifications. Our targeted follow-up strategy has proven to be very efficient in making use of scarce HST time to secure a reliable sample of z ˜ 9-10 galaxies. Through extensive simulations, we replicate the selection process for our sample (both the preselection and follow-up) and use it to improve current estimates for the volume density of bright z ˜ 9 and z ˜ 10 galaxies. The volume densities we find are 5{}_-2⁺³× and {8}_-3⁺⁹× lower, respectively, than those found at z ˜ 8. When compared with the best-fit evolution (i.e., d {{log}}₁₀ {? }_{UV}/{dz}=-0.29+/- 0.02) in the

ID: 138786
Type: article
Authors: Megeath, S. T.; Gutermuth, R.; Muzerolle, J.; Kryukova, E.; Hora, Joseph L.; Allen, L. E.; Flaherty, K.; Hartmann, L.; Myers, P. C.; Pipher, J. L.; Stauffer, J.; Young, E. T.; Fazio, Giovanni G.
Abstract: We analyze the spatial distribution of dusty young stellar objects (YSOs) identified in the Spitzer Survey of the Orion Molecular clouds, augmenting these data with Chandra X-ray observations to correct for incompleteness in dense clustered regions. We also devise a scheme to correct for spatially varying incompleteness when X-ray data are not available. The local surface densities of the YSOs range from 1 pc^-2 to over 10,000 pc^-2, with protostars tending to be in higher density regions. This range of densities is similar to other surveyed molecular clouds with clusters, but broader than clouds without clusters. By identifying clusters and groups as continuous regions with surface densities >=10 pc^-2, we find that 59% of the YSOs are in the largest cluster, the Orion Nebula Cluster (ONC), while 13% of the YSOs are found in a distributed population. A lower fraction of protostars in the distributed population is evidence that it is somewhat older than the groups and clusters. An examination of the structural properties of the clusters and groups shows that the peak surface densities of the clusters increase approximately linearly with the number of members. Furthermore, all clusters with more than 70 members exhibit asymmetric and/or highly elongated structures. The ONC becomes azimuthally symmetric in the inner 0.1 pc, suggesting that the cluster is only ~2 Myr in age. We find that the star formation efficiency (SFE) of the Orion B cloud is unusually low, and that the SFEs of individual groups and clusters are an order of magnitude higher than those of the clouds. Finally, we discuss the relationship between the young low mass stars in the Orion clouds and the Orion OB 1 association, and we determine upper limits to the fraction of disks that may be affected by UV radiation from OB stars or dynamical interactions in dense, clustered regions.