TY - JOUR
T1 - ON R - W1 AS A DIAGNOSTIC to DISCOVER OBSCURED ACTIVE GALACTIC NUCLEI in WIDE-AREA X-RAY SURVEYS
AU - LaMassa, Stephanie M.
AU - Civano, Francesca
AU - Brusa, Marcella
AU - Stern, Daniel
AU - Glikman, Eilat
AU - Gallagher, Sarah
AU - Urry, C. Meg
AU - Cales, Sabrina
AU - Cappelluti, Nico
AU - Cardamone, Carolin
AU - Comastri, Andrea
AU - Farrah, Duncan
AU - Greene, Jenny E.
AU - Komossa, S.
AU - Merloni, Andrea
AU - Mroczkowski, Tony
AU - Natarajan, Priyamvada
AU - Richards, Gordon
AU - Salvato, Mara
AU - Schawinski, Kevin
AU - Treister, Ezequiel
N1 - Funding Information:
S.M.L. acknowledges support from grant number NNX15AJ40G. M.B. acknowledges support from the FP7 Career Integration Grant "eEASy" (CIG 321913). Support for T.M. comes from a National Research Council Research Associateship Award at the Naval Research Laboratory. K.S. gratefully acknowledges support from Swiss National Science Foundation Professorship grant PP00P2-138979/1. Support for the work of E.T. was provided by the Center of Excellence in Astrophysics and Associated Technologies (PFB 06) and by the CONICYT Anillo project ACT1101. Funding for the SDSS and SDSS-II has been provided by the Alfred P. Sloan Foundation, the Participating Institutions, the National Science Foundation, the U.S. Department of Energy, the National Aeronautics and Space Administration, the Japanese Monbukagakusho, the Max Planck Society, and the Higher Education Funding Council for England. The SDSS Web site is http://www.sdss3.org/. The SDSS is managed by the Astrophysical Research Consortium for the Participating Institutions. The Participating Institutions are the American Museum of Natural History, Astrophysical Institute Potsdam, University of Basel, University of Cambridge, Case Western Reserve University, University of Chicago, Drexel University, Fermilab, the Institute for Advanced Study, the Japan Participation Group, Johns Hopkins University, the Joint Institute for Nuclear Astrophysics, the Kavli Institute for Particle Astrophysics and Cosmology, the Korean Scientist Group, the Chinese Academy of Sciences (LAMOST), Los Alamos National Laboratory, the Max-Planck-Institute for Astronomy (MPIA), the Max-PlanckInstitute for Astrophysics (MPA), New Mexico State University, Ohio State University, University of Pittsburgh, University of Portsmouth, Princeton University, the United States Naval Observatory, and the University of Washington. Funding for SDSS-III has been provided by the Alfred P. Sloan Foundation, the Participating Institutions, the National Science Foundation, and the U.S. Department of Energy Office of Science. The SDSS-III Web site is http://www.sdss3.org/. SDSS-III is managed by the Astrophysical Research Consortium for the Participating Institutions of the SDSS-III Collaboration, including the University of Arizona, the Brazilian Participation Group, Brookhaven National Laboratory, Carnegie Mellon University, University of Florida, the French Participation Group, the German Participation Group, Harvard University, the Instituto de Astrofisica de Canarias, the Michigan State/Notre Dame/JINA Participation Group, Johns Hopkins University, Lawrence Berkeley National Laboratory, Max Planck Institute for Astrophysics, Max Planck Institute for Extraterrestrial Physics, New Mexico State University, New York University, Ohio State University, Pennsylvania State University, University of Portsmouth, Princeton University, the Spanish Participation Group, University of Tokyo, University of Utah, Vanderbilt University, University of Virginia, University of Washington, and Yale University. This publication makes use of data products from the Wide-field Infrared Survey Explorer, which is a joint project of the University of California, Los Angeles, and the Jet Propulsion Laboratory/California Institute of Technology, funded by the National Aeronautics and Space Administration.
Publisher Copyright:
© 2016. The American Astronomical Society. All rights reserved.
PY - 2016/2/10
Y1 - 2016/2/10
N2 - Capitalizing on the all-sky coverage of WISE and the 35% and 50% sky coverage from Sloan Digital Sky Survey and Pan-STARRS, respectively, we explore the efficacy of mR (optical) - (mid-infrared), hereafter , as a color diagnostic to identify obscured supermassive black hole accretion in wide-area X-ray surveys. We use the ∼16.5 deg2 Stripe 82 X-ray survey data as a test bed to compare with R - K, an oft-used obscured active galactic nucleus (AGN) selection criterion, and examine where different classes of objects lie in this parameter space. Most stars follow a well-defined path in R - K versus space. We demonstrate that optically normal galaxies hosting X-ray AGNs at redshifts can be recovered with an color cut, while they typically are not selected as AGNs based on their colors. Additionally, different observed X-ray luminosity bins favor different regions in parameter space: moderate-luminosity AGNs (1043 erg erg s-1) tend to have red colors, while the highest-luminosity AGNs ( erg s-1) have bluer colors; higher spectroscopic completeness of the Stripe 82X sample is needed to determine whether this is a selection effect or an intrinsic property. Finally, we parameterize X-ray obscuration of Stripe 82X AGNs by calculating their hardness ratios (HRs) and find no clear trends between HR and optical reddening. Our results will help inform best-effort practices in following up obscured AGN candidates in current and future wide-area, shallow X-ray surveys, including the all-sky eROSITA mission.
AB - Capitalizing on the all-sky coverage of WISE and the 35% and 50% sky coverage from Sloan Digital Sky Survey and Pan-STARRS, respectively, we explore the efficacy of mR (optical) - (mid-infrared), hereafter , as a color diagnostic to identify obscured supermassive black hole accretion in wide-area X-ray surveys. We use the ∼16.5 deg2 Stripe 82 X-ray survey data as a test bed to compare with R - K, an oft-used obscured active galactic nucleus (AGN) selection criterion, and examine where different classes of objects lie in this parameter space. Most stars follow a well-defined path in R - K versus space. We demonstrate that optically normal galaxies hosting X-ray AGNs at redshifts can be recovered with an color cut, while they typically are not selected as AGNs based on their colors. Additionally, different observed X-ray luminosity bins favor different regions in parameter space: moderate-luminosity AGNs (1043 erg erg s-1) tend to have red colors, while the highest-luminosity AGNs ( erg s-1) have bluer colors; higher spectroscopic completeness of the Stripe 82X sample is needed to determine whether this is a selection effect or an intrinsic property. Finally, we parameterize X-ray obscuration of Stripe 82X AGNs by calculating their hardness ratios (HRs) and find no clear trends between HR and optical reddening. Our results will help inform best-effort practices in following up obscured AGN candidates in current and future wide-area, shallow X-ray surveys, including the all-sky eROSITA mission.
KW - X-rays: galaxies
KW - X-rays: general
KW - galaxies: active
KW - infrared: galaxies
KW - quasars: general
KW - quasars: supermassive black holes
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U2 - 10.3847/0004-637X/818/1/88
DO - 10.3847/0004-637X/818/1/88
M3 - Article
AN - SCOPUS:84959202462
SN - 0004-637X
VL - 818
JO - Astrophysical Journal
JF - Astrophysical Journal
IS - 1
M1 - 88
ER -