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Showing 1-20 of about 61 results.
Spectral Implications of Atomic Uncertainties in Optically Thin Hot PlasmasHeuer, KeriFoster, Adam R.Smith, RandallDOI: info:10.3847/1538-4357/abcaffv. 9083
Heuer, Keri, Foster, Adam R., and Smith, Randall. 2021. "Spectral Implications of Atomic Uncertainties in Optically Thin Hot Plasmas." The Astrophysical Journal 908:3. https://doi.org/10.3847/1538-4357/abcaff
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).
The auto- and cross-angular power spectrum of the Cas A supernova remnant in radio and X-raySaha, PreethaBharadwaj, SomnathChakravorty, SusmitaRoy, NirupamChoudhuri, SamirGünther, Hans MoritzSmith, Randall K.DOI: info:10.1093/mnras/stab446v. 5025313–5324
Saha, Preetha, Bharadwaj, Somnath, Chakravorty, Susmita, Roy, Nirupam, Choudhuri, Samir, Günther, Hans Moritz, and Smith, Randall K. 2021. "The auto- and cross-angular power spectrum of the Cas A supernova remnant in radio and X-ray." Monthly Notices of the Royal Astronomical Society 502:5313– 5324. https://doi.org/10.1093/mnras/stab446
ID: 159263
Type: article
Authors: Saha, Preetha; Bharadwaj, Somnath; Chakravorty, Susmita; Roy, Nirupam; Choudhuri, Samir; Günther, Hans Moritz; Smith, Randall K.
Abstract: The shell type supernova remnant (SNR) Cas A exhibits structures at nearly all angular scales. Previous studies show the angular power spectrum (C) of the radio emission to be a broken power law, consistent with MHD turbulence. The break has been identified with the transition from 2D to 3D turbulence at the angular scale corresponding to the shell thickness. Alternatively, this can also be explained as 2D inverse cascade driven by energy injection from knot-shock interactions. Here we present C measured from archival VLA 5-GHz (C band) data, and Chandra X-ray data in the energy ranges ${\rm A}=0.6{-}1.0$ and ${\rm B} =4.2{-}6.0 \,{\rm keV}$ , both of which are continuum dominated. The different emissions all trace fluctuations in the underlying plasma and possibly also the magnetic field, and we expect them to be correlated. We quantify this using the cross-C between the different emissions. We find that X-ray B is strongly correlated with both radio and X-ray A; however, X-ray A is only very weakly correlated with radio. This supports a picture where X-ray A is predominantly thermal bremsstrahlung, whereas X-ray B is a composite of thermal bremsstrahlung and non-thermal synchrotron emission. The various C measured here, all show a broken power-law behaviour. However, the slopes are typically shallower than those in radio and the position of the break also corresponds to smaller angular scales. These findings provide observational inputs regarding the nature of turbulence and the emission mechanisms in Cas A.
The Athena space X-ray observatory and the astrophysics of hot plasmaBarret, DidierDecourchelle, AnneFabian, AndyGuainazzi, MatteoNandra, KirpalSmith, Randallden Herder, Jan-WillemDOI: info:10.1002/asna.202023782v. 341224–235
Barret, Didier, Decourchelle, Anne, Fabian, Andy, Guainazzi, Matteo, Nandra, Kirpal, Smith, Randall, and den Herder, Jan-Willem. 2020. "The Athena space X-ray observatory and the astrophysics of hot plasma." Astronomische Nachrichten 341:224– 235. https://doi.org/10.1002/asna.202023782
ID: 156228
Type: article
Authors: Barret, Didier; Decourchelle, Anne; Fabian, Andy; Guainazzi, Matteo; Nandra, Kirpal; Smith, Randall; den Herder, Jan-Willem
Abstract: The properties (temperature, density, chemical composition, velocity) of hot astrophysical plasma and the physical processes affecting them (heating/cooling, turbulence, shocks, acceleration) can be probed by high-resolution X-ray spectroscopy, to be complemented by high-spatial- resolution imaging. The paper presents the status of the European Space Agency's Advanced Telescope for High Energy Astrophysics (Athena) mission, particularly focusing on the science performance of its two focal-plane instruments for studies of extended X-ray sources: the wide- field imager and the X-ray integral field unit. This paper then provides a brief summary of the breakthroughs expected with Athena on the astrophysics of hot plasma, building on the vast heritage of the discoveries and revolutionary results obtained by Chandra and XMM-Newton in this field. As of November 12, 2019, Athena successfully concluded its feasibility study, and has since then moved into the definition phase, with a launch date scheduled in the early 2030s.
Deep XMM-Newton Observations Reveal the Origin of Recombining Plasma in the Supernova Remnant W44Okon, HiromichiTanaka, TakaakiUchida, HiroyukiYamaguchi, HiroyaTsuru, Takeshi GoSeta, MasumichiSmith, Randall K.Yoshiike, SatoshiOrlando, SalvatoreBocchino, FabrizioMiceli, MarcoDOI: info:10.3847/1538-4357/ab6987v. 89062
Okon, Hiromichi, Tanaka, Takaaki, Uchida, Hiroyuki, Yamaguchi, Hiroya, Tsuru, Takeshi Go, Seta, Masumichi, Smith, Randall K., Yoshiike, Satoshi, Orlando, Salvatore, Bocchino, Fabrizio, and Miceli, Marco. 2020. "Deep XMM-Newton Observations Reveal the Origin of Recombining Plasma in the Supernova Remnant W44." The Astrophysical Journal 890:62. https://doi.org/10.3847/1538-4357/ab6987
ID: 155827
Type: article
Authors: Okon, Hiromichi; Tanaka, Takaaki; Uchida, Hiroyuki; Yamaguchi, Hiroya; Tsuru, Takeshi Go; Seta, Masumichi; Smith, Randall K.; Yoshiike, Satoshi; Orlando, Salvatore; Bocchino, Fabrizio; Miceli, Marco
Abstract: Recent X-ray studies have revealed overionized recombining plasmas in a dozen mixed-morphology (MM) supernova remnants (SNRs). However, the physical process of the overionization has not yet been fully understood. Here we report on spatially resolved spectroscopy of X-ray emission from W44, one of the overionized MM SNRs, using XMM-Newton data from deep observations, with the aim of clarifying the physical origin of the overionization. We find that combination of low electron temperature and low recombination timescale is achieved in the region interacting with dense molecular clouds. Moreover, a clear anticorrelation between the electron temperature and the recombination timescale is obtained from each of the regions with and without the molecular clouds. The results are well explained if the plasma was overionized by rapid cooling through thermal conduction with the dense clouds hit by the blast wave of W44. Given that a few other overionized SNRs show evidence for adiabatic expansion as the major driver of the rapid cooling, our new result indicates that both processes can contribute to overionization in SNRs, with the dominant channel depending on the evolutionary stage.
Roadmap on cosmic EUV and x-ray spectroscopySmith, RandallHahn, MichaelRaymond, JohnKallman, T.Ballance, C. P.Polito, VanessaDel Zanna, GiulioGu, LiyiHell, NatalieCumbee, RenataBetancourt-Martinez, GabrieleCostantini, ElisaCorrales, LiaDOI: info:10.1088/1361-6455/ab69aav. 53092001
Smith, Randall, Hahn, Michael, Raymond, John, Kallman, T., Ballance, C. P., Polito, Vanessa, Del Zanna, Giulio, Gu, Liyi, Hell, Natalie, Cumbee, Renata, Betancourt-Martinez, Gabriele, Costantini, Elisa, and Corrales, Lia. 2020. "Roadmap on cosmic EUV and x-ray spectroscopy." Journal of Physics B Atomic Molecular Physics 53:092001. https://doi.org/10.1088/1361-6455/ab69aa
ID: 157649
Type: article
Authors: Smith, Randall; Hahn, Michael; Raymond, John; Kallman, T.; Ballance, C. P.; Polito, Vanessa; Del Zanna, Giulio; Gu, Liyi; Hell, Natalie; Cumbee, Renata; Betancourt-Martinez, Gabriele; Costantini, Elisa; Corrales, Lia
Abstract: Cosmic EUV/x-ray spectroscopists, including both solar and astrophysical analysts, have a wide range of high-resolution and high-sensitivity tools in use and a number of new facilities in development for launch. As this bandpass requires placing the spectrometer beyond the Earth's atmosphere, each mission represents a major investment by a national space agency such as NASA, ESA, or JAXA, and more typically a collaboration between two or three. In general justifying new mission requires an improvement in capabilities of at least an order of magnitude, but the sensitivity of these existing missions are already taxing existing atomic data quantity and accuracy. This roadmap reviews the existing missions, showing how in a number of areas atomic data limits the science that can be performed. The missions that will be launched in the coming Decade will without doubt require both more and improved measurements of wavelengths and rates, along with theoretical calculations of collisional and radiative cross sections for a wide range of processes.
Laboratory Measurements of X-Ray Emission from Highly Charged Argon IonsBulbul, EsraFoster, AdamBrown, Gregory V.Bautz, Mark W.Beiersdorfer, PeterHell, NatalieKilbourne, CarolineKraft, RalphKelley, RichardLeutenegger, Maurice A.Miller, Eric D.Porter, F. ScottSmith, Randall K.DOI: info:10.3847/1538-4357/aaee7dv. 87021
Bulbul, Esra, Foster, Adam, Brown, Gregory V., Bautz, Mark W., Beiersdorfer, Peter, Hell, Natalie, Kilbourne, Caroline, Kraft, Ralph, Kelley, Richard, Leutenegger, Maurice A., Miller, Eric D., Porter, F. Scott, and Smith, Randall K. 2019. "Laboratory Measurements of X-Ray Emission from Highly Charged Argon Ions." The Astrophysical Journal 870:21. https://doi.org/10.3847/1538-4357/aaee7d
ID: 150421
Type: article
Authors: Bulbul, Esra; Foster, Adam; Brown, Gregory V.; Bautz, Mark W.; Beiersdorfer, Peter; Hell, Natalie; Kilbourne, Caroline; Kraft, Ralph; Kelley, Richard; Leutenegger, Maurice A.; Miller, Eric D.; Porter, F. Scott; Smith, Randall K.
Abstract: Uncertainties in atomic models will introduce noticeable additional systematics in calculating the flux of weak dielectronic recombination (DR) satellite lines, affecting the detection and flux measurements of other weak spectral lines. One important example is the Ar XVII Heβ DR, which is expected to be present in emission from the hot intracluster medium of galaxy clusters and could impact measurements of the flux of the 3.5 keV line that has been suggested as a secondary emission from a dark matter interaction. We perform a set of experiments using the Lawrence Livermore National Laboratory’s electron beam ion trap (EBIT-I) and the X-ray Spectrometer quantum calorimeter (XRS/EBIT) to test the Ar XVII Heβ DR origin of the 3.5 keV line. We measured the X-ray emission following resonant DR onto helium-like and lithium-like Argon using EBIT-I’s Maxwellian simulator mode at a simulated electron temperature of T e = 1.74 keV. The measured flux of the Ar XVII Heβ DR lined is too weak to account for the flux in the 3.5 keV line, assuming reasonable plasma parameters. We, therefore, rule out Ar XVII Heβ DR as a significant contributor to the 3.5 keV line. A comprehensive comparison between the atomic theory and the EBIT experiment results is also provided.
X-Ray Spectra from Plasmas with High-energy Electrons: κ-distributions and e−─e− BremsstrahlungCui, XiaohongFoster, Adam R.Yuasa, TakayukiSmith, Randall K.DOI: info:10.3847/1538-4357/ab5304v. 887182
Cui, Xiaohong, Foster, Adam R., Yuasa, Takayuki, and Smith, Randall K. 2019. "X-Ray Spectra from Plasmas with High-energy Electrons: κ-distributions and e─e Bremsstrahlung." The Astrophysical Journal 887:182. https://doi.org/10.3847/1538-4357/ab5304
ID: 154508
Type: article
Authors: Cui, Xiaohong; Foster, Adam R.; Yuasa, Takayuki; Smith, Randall K.
Abstract: Shocks, turbulence, and winds all influence the electron velocity distribution in hot plasmas, exciting lower-energy electrons and generating a high-energy (typically power-law) tail. This effect, typically described as a κ distribution can affect both the line and continuum X-ray spectra emitted by the plasma. Hahn & Savin proposed a "Maxwellian decomposition" to generate the rate coefficients of κ distributions. Using their method and the AtomDB atomic database, we have developed a general model to calculate the emission from a plasma with a κ distribution. We compare our κ results for the charge state distribution and spectra of oxygen with those from KAPPA package with the ion data available within the CHIANTI atomic database. Sufficiently energetic electrons, created either in a κ distribution or merely a very hot Maxwellian plasma, can also emit via electron─electron (e─e) bremsstrahlung, a process not previously included in AtomDB. We have added this process to AtomDB and apply it to calculate the temperature gradients, as well as the total spectra from the post-shock regions of an accreting magnetic cataclysmic variable. We find the contribution of e─e bremsstrahlung to the total spectra exceeds 10% at KT ∼ 100 keV, with the total emissivity in the post-shock accretion stream differing by more than 10% at energies above 60 keV.
SIXTE: a generic X-ray instrument simulation toolkitDauser, ThomasFalkner, SebastianLorenz, MaximilianKirsch, ChristianPeille, PhilippeCucchetti, EdoardoSchmid, ChristianBrand, ThorstenOertel, MirjamSmith, RandallWilms, JörnDOI: info:10.1051/0004-6361/201935978v. 630A66
Dauser, Thomas, Falkner, Sebastian, Lorenz, Maximilian, Kirsch, Christian, Peille, Philippe, Cucchetti, Edoardo, Schmid, Christian, Brand, Thorsten, Oertel, Mirjam, Smith, Randall, and Wilms, Jörn. 2019. "SIXTE: a generic X-ray instrument simulation toolkit." Astronomy and Astrophysics 630:A66. https://doi.org/10.1051/0004-6361/201935978
ID: 154400
Type: article
Authors: Dauser, Thomas; Falkner, Sebastian; Lorenz, Maximilian; Kirsch, Christian; Peille, Philippe; Cucchetti, Edoardo; Schmid, Christian; Brand, Thorsten; Oertel, Mirjam; Smith, Randall; Wilms, Jörn
Abstract: We give an overview of the SImulation of X-ray TElescopes (SIXTE) software package, a generic, mission-independent Monte Carlo simulation toolkit for X-ray astronomical instrumentation. The package is based on a modular approach for the source definition, the description of the optics, and the detector type such that new missions can be easily implemented. The targets to be simulated are stored in a flexible input format called SIMPUT. Based on this source definition, a sample of photons is produced and then propagated through the optics. In order to model the detection process, the software toolkit contains modules for various detector types, ranging from proportional counter and Si-based detectors, to more complex descriptions like transition edge sensor (TES) devices. The implementation of characteristic detector effects and a detailed modeling of the read-out process allow for representative simulations and therefore enable the analysis of characteristic features, such as for example pile-up, and their impact on observations. We present an overview of the implementation of SIXTE from the input source, the imaging, and the detection process, highlighting the modular approach taken by the SIXTE software package. In order to demonstrate the capabilities of the simulation software, we present a selection of representative applications, including the all-sky survey of eROSITA and a study of pile-up effects comparing the currently operating XMM-Newton with the planned Athena-WFI instrument. A simulation of a galaxy cluster with the Athena-X-IFU shows the capability of SIXTE to predict the expected performance of an observation for a complex source with a spatially varying spectrum and our current knowledge of the future instrument. The SIXTE code is available at http://https://github.com/thdauser/sixte/
Detection of the Missing Baryons toward the Sightline of H1821+643Kovács, Orsolya E.Bogdán, ÁkosSmith, Randall K.Kraft, Ralph P.Forman, William R.DOI: info:10.3847/1538-4357/aaef78v. 87283
Kovács, Orsolya E., Bogdán, Ákos, Smith, Randall K., Kraft, Ralph P., and Forman, William R. 2019. "Detection of the Missing Baryons toward the Sightline of H1821+643." The Astrophysical Journal 872:83. https://doi.org/10.3847/1538-4357/aaef78
ID: 150504
Type: article
Authors: Kovács, Orsolya E.; Bogdán, Ákos; Smith, Randall K.; Kraft, Ralph P.; Forman, William R.
Abstract: Based on constraints from Big Bang nucleosynthesis and the cosmic microwave background, the baryon content of the high-redshift Universe can be precisely determined. However, at low redshift, about one-third of the baryons remain unaccounted for, which poses the long-standing missing baryon problem. The missing baryons are believed to reside in large-scale filaments in the form of warm-hot intergalactic medium (WHIM). In this work, we employ a novel stacking approach to explore the hot phases of the WHIM. Specifically, we utilize the 470 ks Chandra LETG data of the luminous quasar, H 1821+643, along with previous measurements of UV absorption line systems and spectroscopic redshift measurements of galaxies toward the quasar’s sightline. We repeatedly blueshift and stack the X-ray spectrum of the quasar corresponding to the redshifts of the 17 absorption line systems. Thus, we obtain a stacked spectrum with 8.0 Ms total exposure, which allows us to probe X-ray absorption lines with unparalleled sensitivity. Based on the stacked data, we detect an O VII absorption line that exhibits a Gaussian line profile and is statistically significant at the 3.3σ level. Since the redshifts of the UV absorption line systems were known a priori, this is the first definitive detection of an X-ray absorption line originating from the WHIM. The equivalent width of the O VII line is (4.1 ± 1.3) mÅ, which corresponds to an O VII column density of (1.4+/- 0.4)× {10}15 {cm}}-2. We constrain the absorbing gas to have a density of {n}{{H}}=(1-2)× {10}-6 {cm}}-3 for a single WHIM filament. We derive {{{Ω }}}{{b}}({{O}} {{VII}})=(0.0023+/- 0.0007){≤ft[{f}{{O}{{VII}}}Z/{Z}ȯ \right]}-1 for the cosmological mass density of O VII, assuming that all 17 systems contribute equally.
Nonequilibrium Ionization in Mixed-morphology Supernova RemnantsZhang, Gao-YuanSlavin, Jonathan D.Foster, AdamSmith, Randall K.ZuHone, John A.Zhou, PingChen, YangDOI: info:10.3847/1538-4357/ab0f9av. 87581
Zhang, Gao-Yuan, Slavin, Jonathan D., Foster, Adam, Smith, Randall K., ZuHone, John A., Zhou, Ping, and Chen, Yang. 2019. "Nonequilibrium Ionization in Mixed-morphology Supernova Remnants." The Astrophysical Journal 875:81. https://doi.org/10.3847/1538-4357/ab0f9a
ID: 155248
Type: article
Authors: Zhang, Gao-Yuan; Slavin, Jonathan D.; Foster, Adam; Smith, Randall K.; ZuHone, John A.; Zhou, Ping; Chen, Yang
Abstract: The mixed-morphology class of supernova remnants (MMSNRs) comprises a substantial fraction of observed remnants, but there is no consensus on their origin as yet. A clue to their nature is the presence of regions that show X-ray evidence of recombining plasmas. Recent calculations of remnant evolution in a cloudy interstellar medium that included thermal conduction but not nonequilibrium ionization (NEI) showed promise in explaining observed surface brightness distributions but could not determine whether recombining plasmas were present. In this paper, we present numerical hydrodynamic models of MMSNRs in 2D and 3D, including explicit calculation of NEI effects. Both the spatial ionization distribution and temperature-density diagrams show that recombination occurs inside the simulated MMSNR and that both adiabatic expansion and thermal conduction cause recombination, albeit in different regions. Features created by the adiabatic expansion stand out in the spatial and temperature-density diagrams, but thermal conduction also plays a role. Thus, thermal conduction and adiabatic expansion both contribute significantly to the cooling of high-temperature gas. Realistic observational data are simulated with both spatial and spectral input from various regions. We also discuss the possibility of analyzing the sources of recombination and dominant hydrodynamic processes in observations using temperature-density diagrams and spatial maps.
Searching for the 3.5 keV Line in the Deep Fields with Chandra: The 10 Ms ObservationsCappelluti, NicoBulbul, EsraFoster, AdamNatarajan, PriyamvadaUrry, Megan C.Bautz, Mark W.Civano, FrancescaMiller, EricSmith, Randall K.DOI: info:10.3847/1538-4357/aaaa68v. 854179
Cappelluti, Nico, Bulbul, Esra, Foster, Adam, Natarajan, Priyamvada, Urry, Megan C., Bautz, Mark W., Civano, Francesca, Miller, Eric, and Smith, Randall K. 2018. "Searching for the 3.5 keV Line in the Deep Fields with Chandra: The 10 Ms Observations." The Astrophysical Journal 854:179. https://doi.org/10.3847/1538-4357/aaaa68
ID: 145794
Type: article
Authors: Cappelluti, Nico; Bulbul, Esra; Foster, Adam; Natarajan, Priyamvada; Urry, Megan C.; Bautz, Mark W.; Civano, Francesca; Miller, Eric; Smith, Randall K.
Abstract: We report a systematic search for an emission line around 3.5 keV in the spectrum of the cosmic X-ray background using a total of ∼10 Ms Chandra observations toward the COSMOS Legacy and Extended Chandra Deep Field South survey fields. We find marginal evidence of a feature at an energy of ∼3.51 keV with a significance of 2.5–3σ, depending on the choice of statistical treatment. The line intensity is best fit at (8.8 ± 2.9) × 10‑7 ph cm‑2 s‑1 when using a simple Δχ 2 or {10.2}-0.4+0.2× {10}-7 ph cm‑2 s‑1 when Markov chain Monte Carlo is used. Based on our knowledge of Chandra and the reported detection of the line by other instruments, an instrumental origin for the line remains unlikely. We cannot, however, rule out a statistical fluctuation, and in that case our results provide a 3σ upper limit at 1.85 × 10‑6 ph cm‑2 s‑1. We discuss the interpretation of this observed line in terms of the iron line background, S XVI charge exchange, as well as potentially being from sterile neutrino decay. We note that our detection is consistent with previous measurements of this line toward the Galactic center and can be modeled as the result of sterile neutrino decay from the Milky Way for the dark matter distribution modeled as a Navarro–Frenk–White profile. For this case, we estimate a mass m ν ∼ 7.01 keV and a mixing angle sin2(2θ) = (0.83–2.75) × 10‑10. These derived values are in agreement with independent estimates from galaxy clusters, the Galactic center, and M31.
The Ultra-fast Outflow of the Quasar PG 1211+143 as Viewed by Time-averaged Chandra Grating SpectroscopyDanehkar, AshkbizNowak, Michael A.Lee, Julia C.Kriss, Gerard A.Young, Andrew J.Hardcastle, Martin J.Chakravorty, SusmitaFang, TaotaoNeilsen, JosephRahoui, FaridSmith, Randall K.DOI: info:10.3847/1538-4357/aaa427v. 853165
Danehkar, Ashkbiz, Nowak, Michael A., Lee, Julia C., Kriss, Gerard A., Young, Andrew J., Hardcastle, Martin J., Chakravorty, Susmita, Fang, Taotao, Neilsen, Joseph, Rahoui, Farid, and Smith, Randall K. 2018. "The Ultra-fast Outflow of the Quasar PG 1211+143 as Viewed by Time-averaged Chandra Grating Spectroscopy." The Astrophysical Journal 853:165. https://doi.org/10.3847/1538-4357/aaa427
ID: 145804
Type: article
Authors: Danehkar, Ashkbiz; Nowak, Michael A.; Lee, Julia C.; Kriss, Gerard A.; Young, Andrew J.; Hardcastle, Martin J.; Chakravorty, Susmita; Fang, Taotao; Neilsen, Joseph; Rahoui, Farid; Smith, Randall K.
Abstract: We present a detailed X-ray spectral study of the quasar PG 1211+143 based on Chandra High Energy Transmission Grating Spectrometer (HETGS) observations collected in a multi-wavelength campaign with UV data using the Hubble Space Telescope Cosmic Origins Spectrograph (HST-COS) and radio bands using the Jansky Very Large Array (VLA). We constructed a multi-wavelength ionizing spectral energy distribution using these observations and archival infrared data to create XSTAR photoionization models specific to the PG 1211+143 flux behavior during the epoch of our observations. Our analysis of the Chandra-HETGS spectra yields complex absorption lines from H-like and He-like ions of Ne, Mg, and Si, which confirm the presence of an ultra-fast outflow (UFO) with a velocity of approximately ‑17,300 km s‑1 (outflow redshift z out ∼ ‑0.0561) in the rest frame of PG 1211+143. This absorber is well described by an ionization parameter {log}ξ ∼ 2.9 {erg} {{{s}}}-1 {cm} and column density {log}{N}{{H}}∼ 21.5 {{cm}}-2. This corresponds to a stable region of the absorber's thermal stability curve, and furthermore its implied neutral hydrogen column is broadly consistent with a broad Lyα absorption line at a mean outflow velocity of approximately ‑16,980 km s‑1 detected by our HST-COS observations. Our findings represent the first simultaneous detection of a UFO in both X-ray and UV observations. Our VLA observations provide evidence for an active jet in PG 1211+143, which may be connected to the X-ray and UV outflows; this possibility can be evaluated using very-long-baseline interferometric observations.
Detection of polarized gamma-ray emission from the Crab nebula with the Hitomi Soft Gamma-ray DetectorHitomi CollaborationAharonian, FelixAkamatsu, HirokiAkimoto, FumieAllen, Steven W.Angelini, LorellaAudard, MarcAwaki, HisamitsuAxelsson, MagnusBamba, AyaBautz, Marshall W.Blandford, RogerBrenneman, Laura W.Brown, Gregory V.Bulbul, EsraCackett, Edward M.Chernyakova, MariaChiao, Meng P.Coppi, Paolo S.Costantini, Elisade Plaa, Jellede Vries, Cor P.den Herder, Jan-WillemDone, ChrisDotani, TadayasuEbisawa, KenEckart, Megan E.Enoto, TeruakiEzoe, YuichiroFabian, Andrew C.Ferrigno, CarloFoster, Adam R.Fujimoto, RyuichiFukazawa, YasushiFuruzawa, AkihiroGaleazzi, MassimilianoGallo, Luigi C.Gandhi, PoshakGiustini, MargheritaGoldwurm, AndreaGu, LiyiGuainazzi, MatteoHaba, YoshitoHagino, KouichiHamaguchi, KenjiHarrus, Ilana M.Hatsukade, IsamuHayashi, KatsuhiroHayashi, TakayukiHayashida, KiyoshiHiraga, Junko S.Hornschemeier, AnnHoshino, AkioHughes, John P.Ichinohe, YutoIizuka, RyoInoue, HajimeInoue, YoshiyukiIshida, ManabuIshikawa, KumiIshisaki, YoshitakaIwai, MasachikaKaastra, JelleKallman, TimKamae, TsuneyoshiKataoka, JunKatsuda, SatoruKawai, NobuyukiKelley, Richard L.Kilbourne, Caroline A.Kitaguchi, TakaoKitamoto, ShunjiKitayama, TetsuKohmura, TakayoshiKokubun, MotohideKoyama, KatsujiKoyama, ShuKretschmar, PeterKrimm, Hans A.Kubota, AyaKunieda, HideyoLaurent, PhilippeLee, Shiu-HangLeutenegger, Maurice A.Limousin, OlivierLoewenstein, MichaelLong, Knox S.Lumb, DavidMadejski, GregMaeda, YoshitomoMaier, DanielMakishima, KazuoMarkevitch, MaximMatsumoto, HironoriMatsushita, KyokoMcCammon, DanMcNamara, Brian R.Mehdipour, MissaghMiller, Eric D.Miller, Jon M.Mineshige, ShinMitsuda, KazuhisaMitsuishi, IkuyukiMiyazawa, TakuyaMizuno, TsunefumiMori, HideyukiMori, KojiMukai, KojiMurakami, HiroshiMushotzky, Richard F.Nakagawa, TakaoNakajima, HiroshiNakamori, TakeshiNakashima, ShinyaNakazawa, KazuhiroNobukawa, Kumiko K.Nobukawa, MasayoshiNoda, HirofumiOdaka, HirokazuOhashi, TakayaOhno, MasanoriOkajima, TakashiOta, NaomiOzaki, MasanobuPaerels, FritsPaltani, StéphanePetre, RobertPinto, CiroPorter, Frederick S.Pottschmidt, KatjaReynolds, Christopher S.Safi-Harb, SamarSaito, ShinyaSakai, KazuhiroSasaki, ToruSato, GoroSato, KosukeSato, RieSawada, MakotoSchartel, NorbertSerlemtsos, Peter J.Seta, HiromiShidatsu, MegumiSimionescu, AuroraSmith, Randall K.Soong, YangStawarz, ŁukaszSugawara, YasuharuSugita, SatoshiSzymkowiak, AndrewTajima, HiroyasuTakahashi, HiromitsuTakahashi, TadayukiTakeda, Shin'ichiroTakei, YohTamagawa, ToruTamura, TakayukiTanaka, TakaakiTanaka, YasuoTanaka, Yasuyuki T.Tashiro, Makoto S.Tawara, YuzuruTerada, YukikatsuTerashima, YuichiTombesi, FrancescoTomida, HiroshiTsuboi, YohkoTsujimoto, MasahiroTsunemi, HiroshiTsuru, Takeshi GoUchida, HiroyukiUchiyama, HidekiUchiyama, YasunobuUeda, ShutaroUeda, YoshihiroUno, Shin'ichiroUrry, C. MeganUrsino, EugenioWatanabe, ShinWerner, NorbertWilkins, Dan R.Williams, Brian J.Yamada, ShinyaYamaguchi, HiroyaYamaoka, KazutakaYamasaki, Noriko Y.Yamauchi, MakotoYamauchi, ShigeoYaqoob, TahirYatsu, YoichiYonetoku, DaisukeZhuravleva, IrinaZoghbi, AbderahmenUchida, YuusukeDOI: info:10.1093/pasj/psy118v. 70113
Hitomi Collaboration, Aharonian, Felix, Akamatsu, Hiroki, Akimoto, Fumie, Allen, Steven W., Angelini, Lorella, Audard, Marc, Awaki, Hisamitsu, Axelsson, Magnus, Bamba, Aya, Bautz, Marshall W., Blandford, Roger, Brenneman, Laura W., Brown, Gregory V., Bulbul, Esra, Cackett, Edward M., Chernyakova, Maria, Chiao, Meng P., Coppi, Paolo S., Costantini, Elisa, de Plaa, Jelle, de Vries, Cor P., den Herder, Jan-Willem, Done, Chris, Dotani, Tadayasu et al. 2018. "Detection of polarized gamma-ray emission from the Crab nebula with the Hitomi Soft Gamma-ray Detector." Publications of the Astronomical Society of Japan 70:113. https://doi.org/10.1093/pasj/psy118
ID: 150195
Type: article
Authors: Hitomi Collaboration; Aharonian, Felix; Akamatsu, Hiroki; Akimoto, Fumie; Allen, Steven W.; Angelini, Lorella; Audard, Marc; Awaki, Hisamitsu; Axelsson, Magnus; Bamba, Aya; Bautz, Marshall W.; Blandford, Roger; Brenneman, Laura W.; Brown, Gregory V.; Bulbul, Esra; Cackett, Edward M.; Chernyakova, Maria; Chiao, Meng P.; Coppi, Paolo S.; Costantini, Elisa; de Plaa, Jelle; de Vries, Cor P.; den Herder, Jan-Willem; Done, Chris; Dotani, Tadayasu; Ebisawa, Ken; Eckart, Megan E.; Enoto, Teruaki; Ezoe, Yuichiro; Fabian, Andrew C.; Ferrigno, Carlo; Foster, Adam R.; Fujimoto, Ryuichi; Fukazawa, Yasushi; Furuzawa, Akihiro; Galeazzi, Massimiliano; Gallo, Luigi C.; Gandhi, Poshak; Giustini, Margherita; Goldwurm, Andrea; Gu, Liyi; Guainazzi, Matteo; Haba, Yoshito; Hagino, Kouichi; Hamaguchi, Kenji; Harrus, Ilana M.; Hatsukade, Isamu; Hayashi, Katsuhiro; Hayashi, Takayuki; Hayashida, Kiyoshi; Hiraga, Junko S.; Hornschemeier, Ann; Hoshino, Akio; Hughes, John P.; Ichinohe, Yuto; Iizuka, Ryo; Inoue, Hajime; Inoue, Yoshiyuki; Ishida, Manabu; Ishikawa, Kumi; Ishisaki, Yoshitaka; Iwai, Masachika; Kaastra, Jelle; Kallman, Tim; Kamae, Tsuneyoshi; Kataoka, Jun; Katsuda, Satoru; Kawai, Nobuyuki; Kelley, Richard L.; Kilbourne, Caroline A.; Kitaguchi, Takao; Kitamoto, Shunji; Kitayama, Tetsu; Kohmura, Takayoshi; Kokubun, Motohide; Koyama, Katsuji; Koyama, Shu; Kretschmar, Peter; Krimm, Hans A.; Kubota, Aya; Kunieda, Hideyo; Laurent, Philippe; Lee, Shiu-Hang; Leutenegger, Maurice A.; Limousin, Olivier; Loewenstein, Michael; Long, Knox S.; Lumb, David; Madejski, Greg; Maeda, Yoshitomo; Maier, Daniel; Makishima, Kazuo; Markevitch, Maxim; Matsumoto, Hironori; Matsushita, Kyoko; McCammon, Dan; McNamara, Brian R.; Mehdipour, Missagh; Miller, Eric D.; Miller, Jon M.; Mineshige, Shin; Mitsuda, Kazuhisa; Mitsuishi, Ikuyuki; Miyazawa, Takuya; Mizuno, Tsunefumi; Mori, Hideyuki; Mori, Koji; Mukai, Koji; Murakami, Hiroshi; Mushotzky, Richard F.; Nakagawa, Takao; Nakajima, Hiroshi; Nakamori, Takeshi; Nakashima, Shinya; Nakazawa, Kazuhiro; Nobukawa, Kumiko K.; Nobukawa, Masayoshi; Noda, Hirofumi; Odaka, Hirokazu; Ohashi, Takaya; Ohno, Masanori; Okajima, Takashi; Ota, Naomi; Ozaki, Masanobu; Paerels, Frits; Paltani, Stéphane; Petre, Robert; Pinto, Ciro; Porter, Frederick S.; Pottschmidt, Katja; Reynolds, Christopher S.; Safi-Harb, Samar; Saito, Shinya; Sakai, Kazuhiro; Sasaki, Toru; Sato, Goro; Sato, Kosuke; Sato, Rie; Sawada, Makoto; Schartel, Norbert; Serlemtsos, Peter J.; Seta, Hiromi; Shidatsu, Megumi; Simionescu, Aurora; Smith, Randall K.; Soong, Yang; Stawarz, Łukasz; Sugawara, Yasuharu; Sugita, Satoshi; Szymkowiak, Andrew; Tajima, Hiroyasu; Takahashi, Hiromitsu; Takahashi, Tadayuki; Takeda, Shin'ichiro; Takei, Yoh; Tamagawa, Toru; Tamura, Takayuki; Tanaka, Takaaki; Tanaka, Yasuo; Tanaka, Yasuyuki T.; Tashiro, Makoto S.; Tawara, Yuzuru; Terada, Yukikatsu; Terashima, Yuichi; Tombesi, Francesco; Tomida, Hiroshi; Tsuboi, Yohko; Tsujimoto, Masahiro; Tsunemi, Hiroshi; Tsuru, Takeshi Go; Uchida, Hiroyuki; Uchiyama, Hideki; Uchiyama, Yasunobu; Ueda, Shutaro; Ueda, Yoshihiro; Uno, Shin'ichiro; Urry, C. Megan; Ursino, Eugenio; Watanabe, Shin; Werner, Norbert; Wilkins, Dan R.; Williams, Brian J.; Yamada, Shinya; Yamaguchi, Hiroya; Yamaoka, Kazutaka; Yamasaki, Noriko Y.; Yamauchi, Makoto; Yamauchi, Shigeo; Yaqoob, Tahir; Yatsu, Yoichi; Yonetoku, Daisuke; Zhuravleva, Irina; Zoghbi, Abderahmen; Uchida, Yuusuke
Abstract: We present the results from the Hitomi Soft Gamma-ray Detector (SGD) observation of the Crab nebula. The main part of SGD is a Compton camera, which in addition to being a spectrometer, is capable of measuring polarization of gamma-ray photons. The Crab nebula is one of the brightest X-ray/gamma-ray sources on the sky, and the only source from which polarized X-ray photons have been detected. SGD observed the Crab nebula during the initial test observation phase of Hitomi. We performed data analysis of the SGD observation, SGD background estimation, and SGD Monte Carlo simulations, and successfully detected polarized gamma-ray emission from the Crab nebula with only about 5 ks exposure time. The obtained polarization fraction of the phase-integrated Crab emission (sum of pulsar and nebula emissions) is (22.1% ± 10.6%), and the polarization angle is {110{^{circ}.}7} +{13{^{circ}.}2}/-{13{^{circ}.}0} in the energy range of 60-160 keV (the errors correspond to the 1 σ deviation). The confidence level of the polarization detection was 99.3%. The polarization angle measured by SGD is about one sigma deviation with the projected spin axis of the pulsar, {124{^{circ}.}0} ± {0{^{circ}.}1}.
Effects of interstellar dust scattering on the X-ray eclipses of the LMXB AX J1745.6-2901 in the Galactic CentreJin, ChichuanPonti, GabrieleHaberl, FrankSmith, RandallValencic, LynneDOI: info:10.1093/mnras/sty869v. 4773480–3506
Jin, Chichuan, Ponti, Gabriele, Haberl, Frank, Smith, Randall, and Valencic, Lynne. 2018. "Effects of interstellar dust scattering on the X-ray eclipses of the LMXB AX J1745.6-2901 in the Galactic Centre." Monthly Notices of the Royal Astronomical Society 477:3480– 3506. https://doi.org/10.1093/mnras/sty869
ID: 147892
Type: article
Authors: Jin, Chichuan; Ponti, Gabriele; Haberl, Frank; Smith, Randall; Valencic, Lynne
Abstract: AX J1745.6-2901 is an eclipsing low-mass X-ray binary in the Galactic Centre (GC). It shows significant X-ray excess emission during the eclipse phase, and its eclipse light curve shows an asymmetric shape. We use archival XMM-Newton and Chandra observations to study the origin of these peculiar X-ray eclipsing phenomena. We find that the shape of the observed X-ray eclipse light curves depends on both photon energy and the shape of the source extraction region, and also shows differences between the two instruments. By performing detailed simulations for the time-dependent X-ray dust-scattering halo, as well as directly modelling the observed eclipse and non-eclipse halo profiles of AX J1745.6-2901, we obtained solid evidence that its peculiar eclipse phenomena are indeed caused by the X-ray dust scattering in multiple foreground dust layers along the line of sight (LOS). The apparent dependence on the instruments is caused by different instrumental point spread functions. Our results can be used to assess the influence of dust-scattering in other eclipsing X-ray sources, and raise the importance of considering the timing effects of dust-scattering halo when studying the variability of other X-ray sources in the GC, such as Sgr A*. Moreover, our study of halo eclipse reinforces the existence of a dust layer local to AX J1745.6-2901 as reported by Jin et al. (2017), as well as identifying another dust layer within a few hundred parsecs to the Earth, containing up to several tens of percent LOS dust, which is likely to be associated with the molecular clouds in the Solar neighbourhood. The remaining LOS dust is likely to be associated with the molecular clouds located in the Galactic disc in-between.
Evidence for Rapid Adiabatic Cooling as an Origin of the Recombining Plasma in the Supernova Remnant W49B Revealed by NuSTAR ObservationsYamaguchi, HiroyaTanaka, TakaakiWik, Daniel R.Rho, JeongheeBamba, AyaCastro, DanielSmith, Randall K.Foster, Adam R.Uchida, HiroyukiPetre, RobertWilliams, Brian J.DOI: info:10.3847/2041-8213/aaf055v. 868L35
Yamaguchi, Hiroya, Tanaka, Takaaki, Wik, Daniel R., Rho, Jeonghee, Bamba, Aya, Castro, Daniel, Smith, Randall K., Foster, Adam R., Uchida, Hiroyuki, Petre, Robert, and Williams, Brian J. 2018. "Evidence for Rapid Adiabatic Cooling as an Origin of the Recombining Plasma in the Supernova Remnant W49B Revealed by NuSTAR Observations." Astrophysical Journal Letters 868:L35. https://doi.org/10.3847/2041-8213/aaf055
ID: 150224
Type: article
Authors: Yamaguchi, Hiroya; Tanaka, Takaaki; Wik, Daniel R.; Rho, Jeonghee; Bamba, Aya; Castro, Daniel; Smith, Randall K.; Foster, Adam R.; Uchida, Hiroyuki; Petre, Robert; Williams, Brian J.
Abstract: X-ray observations of supernova remnants (SNRs) in the last decade have shown that the presence of recombining plasmas is somewhat common in a certain type of object. The SNR W49B is the youngest, hottest, and most highly ionized among such objects, and hence provides crucial information about how the recombination phase is reached during the early evolutionary phase of SNRs. In particular, spectral properties of radiative recombination continuum (RRC) from Fe are the key for constraining the detailed plasma conditions. Here we present imaging and spectral studies of W49B with Nuclear Spectroscopic Telescope Array (NuSTAR), utilizing the highest-ever sensitivity to the Fe RRC at ≳8.8 keV. We confirm that the Fe RRC is most prominent at the western part of the SNR because of the lowest electron temperature (∼1.2 keV) achieved there. Our spatially resolved spectral analysis reveals a positive correlation between the electron temperature and the recombination timescale with a uniform initial temperature of ∼4 keV, which is consistent with the rapid adiabatic cooling scenario as an origin of the overionization. This Letter demonstrates NuSTAR’s suitability for studies of thermal emission, in addition to hard nonthermal X-rays, from young and middle-aged SNRs.
Eigenvalue Method for NEI Unit in FLASH CodeZhang, Gao-YuanFoster, AdamSmith, RandallDOI: info:10.3847/1538-4357/aad692v. 86479
Zhang, Gao-Yuan, Foster, Adam, and Smith, Randall. 2018. "Eigenvalue Method for NEI Unit in FLASH Code." The Astrophysical Journal 864:79. https://doi.org/10.3847/1538-4357/aad692
ID: 149172
Type: article
Authors: Zhang, Gao-Yuan; Foster, Adam; Smith, Randall
Abstract: We describe an improved nonequilibrium ionization (NEI) method that we have developed as an optional module for the FLASH magnetohydrodynamic simulation code. The method employs an eigenvalue approach rather than the earlier iterative ordinary differential equation approach to solve the stiff differential equations involved in NEI calculations. The new code also allows the atomic data to be easily updated from the AtomDB database. We compare both the updated atomic data and the methods separately. The new atomic data are shown to make a significant difference in some circumstances, although the general trends remain the same. Additionally, the new method also allows simultaneous calculation of the nonequilibrium radiative cooling, which is not included in the original method. The eigenvalue method improves the calculation efficiency overall with no loss of accuracy. We explore some common ways to present the NEI state with a sample simulation and find that using average ionic charge difference from the equilibrium tends to be the clearest method.
Numerical Simulations of Supernova Remnant Evolution in a Cloudy Interstellar MediumSlavin, Jonathan D.Smith, Randall K.Foster, AdamWinter, Henry D.Raymond, John C.Slane, Patrick O.Yamaguchi, HiroyaDOI: info:10.3847/1538-4357/aa8552v. 84677
Slavin, Jonathan D., Smith, Randall K., Foster, Adam, Winter, Henry D., Raymond, John C., Slane, Patrick O., and Yamaguchi, Hiroya. 2017. "Numerical Simulations of Supernova Remnant Evolution in a Cloudy Interstellar Medium." The Astrophysical Journal 846:77. https://doi.org/10.3847/1538-4357/aa8552
ID: 144719
Type: article
Authors: Slavin, Jonathan D.; Smith, Randall K.; Foster, Adam; Winter, Henry D.; Raymond, John C.; Slane, Patrick O.; Yamaguchi, Hiroya
Abstract: The mixed morphology class of supernova remnants has centrally peaked X-ray emission along with a shell-like morphology in radio emission. White & Long proposed that these remnants are evolving in a cloudy medium wherein the clouds are evaporated via thermal conduction once being overrun by the expanding shock. Their analytical model made detailed predictions regarding temperature, density, and emission profiles as well as shock evolution. We present numerical hydrodynamical models in 2D and 3D including thermal conduction, testing the White & Long model and presenting results for the evolution and emission from remnants evolving in a cloudy medium. We find that, while certain general results of the White & Long model hold, such as the way the remnants expand and the flattening of the X-ray surface brightness distribution, in detail there are substantial differences. In particular we find that the X-ray luminosity is dominated by emission from shocked cloud gas early on, leading to a bright peak, which then declines and flattens as evaporation becomes more important. In addition, the effects of thermal conduction on the intercloud gas, which is not included in the White & Long model, are important and lead to further flattening of the X-ray brightness profile as well as lower X-ray emission temperatures.
Black holes and vacuum cleaners: Using metaphor, relevance, and inquiry in labels for space imagesSmith, Lisa F.Arcand, Kimberly KowalSmith, Benjamin K.Smith, Randall K.Bookbinder, JaySmith, Jeffrey K.DOI: info:10.1037/aca0000130v. 11No. 3359–374
Smith, Lisa F., Arcand, Kimberly Kowal, Smith, Benjamin K., Smith, Randall K., Bookbinder, Jay, and Smith, Jeffrey K. 2017. "Black holes and vacuum cleaners: Using metaphor, relevance, and inquiry in labels for space images." Psychology of Aesthetics, Creativity, and the Arts 11 (3):359– 374. https://doi.org/10.1037/aca0000130
ID: 149441
Type: article
Authors: Smith, Lisa F.; Arcand, Kimberly Kowal; Smith, Benjamin K.; Smith, Randall K.; Bookbinder, Jay; Smith, Jeffrey K.
Abstract: This study extended research on the development of explanatory labels for astronomical images for the nonexpert lay public. The research questions addressed how labels with leading questions/metaphors and relevance to everyday life affect comprehension of the intended message for deep space images, the desire to learn more, and the aesthetic appreciation of images. Participants were a convenience sample of 1,921 respondents solicited from a variety of websites and through social media who completed an online survey that used 4 high-resolution images as stimuli: Sagittarius A*, Solar Flare, Cassiopeia A, and the Pinwheel Galaxy (M101). Participants were randomly assigned initially to 1 of 3 label conditions: the standard label originally written for the image, a label with a leading question containing a metaphor related to the information for the image, or a label that contained a fact about the image relevant to everyday life. Participants were randomly assigned to 1 image and compared all labels for that image. Open-ended items at various points asked participants to pose questions to a hypothetical astronomer. Main findings were that the relevance condition was significantly more likely to increase wanting to learn more; the original label was most likely to increase overall appreciation; and smart phone users were more likely to want to learn more and report increased levels of appreciation. Results are discussed in terms of the need to examine individual viewer characteristics and goals in creating different labels for different audiences.
Capturing the many faces of an exploded star: communicating complex and evolving astronomical dataSmith, LisaArcand, Kimberly KowalSmith, RandallBookbinder, JaySmith, JeffreyDOI: info:10.22323/2.16050202v. 16No. 05
Smith, Lisa, Arcand, Kimberly Kowal, Smith, Randall, Bookbinder, Jay, and Smith, Jeffrey. 2017. "Capturing the many faces of an exploded star: communicating complex and evolving astronomical data." Journal of Science Communication 16 (05):https://doi.org/10.22323/2.16050202
ID: 149350
Type: article
Authors: Smith, Lisa; Arcand, Kimberly Kowal; Smith, Randall; Bookbinder, Jay; Smith, Jeffrey
Abstract: This study explored how different presentations of an object in deep space affect understanding, engagement, and aesthetic appreciation. A total of n = 2,502 respondents to an online survey were randomly assigned to one of 11 versions of Cassiopeia A, comprising 6 images and 5 videos ranging from 3 s to approximately 1 min. Participants responded to initial items regarding what the image looked like, the aesthetic appeal of the image, perceptions of understanding, and how much the participant wanted to learn more. After the image was identified, participants indicated the extent to which the label increased understanding and how well the image represented the object. A final item asked for questions about the image for an astronomer. Results suggest that alternative types of images can and should be used, provided they are accompanied by explanations. Qualitative data indicated that explanations should include information about colors used, size, scale, and location of the object. The results are discussed in terms of science communication to the public in the face of increasing use of technology.
Searching for the 3.5 keV Line in the Stacked Suzaku Observations of Galaxy ClustersBulbul, EsraMarkevitch, MaximFoster, AdamMiller, EricBautz, MarkLoewenstein, MikeRandall, Scott W.Smith, Randall K.DOI: info:10.3847/0004-637X/831/1/55v. 83155
Bulbul, Esra, Markevitch, Maxim, Foster, Adam, Miller, Eric, Bautz, Mark, Loewenstein, Mike, Randall, Scott W., and Smith, Randall K. 2016. "Searching for the 3.5 keV Line in the Stacked Suzaku Observations of Galaxy Clusters." The Astrophysical Journal 831:55. https://doi.org/10.3847/0004-637X/831/1/55
ID: 141917
Type: article
Authors: Bulbul, Esra; Markevitch, Maxim; Foster, Adam; Miller, Eric; Bautz, Mark; Loewenstein, Mike; Randall, Scott W.; Smith, Randall K.
Abstract: We perform a detailed study of the stacked Suzaku observations of 47 galaxy clusters, spanning a redshift range of 0.01-0.45, to search for the unidentified 3.5 keV line. This sample provides an independent test for the previously detected line. We detect a 2? -significant spectral feature at 3.5 keV in the spectrum of the full sample. When the sample is divided into two subsamples (cool-core and non-cool core clusters), the cool-core subsample shows no statistically significant positive residuals at the line energy. A very weak (~ 2? confidence) spectral feature at 3.5 keV is permitted by the data from the non-cool-core clusters sample. The upper limit on a neutrino decay mixing angle of {\sin }2(2? )=6.1× {10}-11 from the full Suzaku sample is consistent with the previous detections in the stacked XMM-Newton sample of galaxy clusters (which had a higher statistical sensitivity to faint lines), M31, and Galactic center, at a 90% confidence level. However, the constraint from the present sample, which does not include the Perseus cluster, is in tension with previously reported line flux observed in the core of the Perseus cluster with XMM-Newton and Suzaku.