Characterizing the WISE-selected heavily obscured quasar population with optical spectroscopy from the Southern African Large Telescope
AuthorHviding, Raphael E.
Hickox, Ryan C.
Hainline, Kevin N.
Carroll, Christopher M.
DiPompeo, Michael A.
Jones, Mackenzie L.
AffiliationUniv Arizona, Steward Observ
MetadataShow full item record
PublisherOXFORD UNIV PRESS
CitationCharacterizing the WISE-selected heavily obscured quasar population with optical spectroscopy from the Southern African Large Telescope 2018, 474 (2):1955 Monthly Notices of the Royal Astronomical Society
Rights© 2017 The Author(s) Published by Oxford University Press on behalf of the Royal Astronomical Society.
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AbstractWe present the results of an optical spectroscopic survey of 46 heavily obscured quasar candidates. Objects are selected using their mid-infrared (mid-IR) colours and magnitudes from the Wide-Field Infrared Survey Explorer (WISE) anzd their optical magnitudes from the Sloan Digital Sky Survey. Candidate Active Galactic Nuclei (AGNs) are selected to have mid-IR colours indicative of quasar activity and lie in a region of mid-IR colour space outside previously published X-ray based selection regions. We obtain optical spectra for our sample using the Robert Stobie Spectrograph on the Southern African Large Telescope. 30 objects (65 per cent) have identifiable emission lines, allowing for the determination of spectroscopic redshifts. Other than one object at z similar to 2.6, candidates have moderate redshifts ranging from z = 0.1 to 0.8 with a median of 0.3. 21 (70 per cent) of our objects with identified redshift (46 per cent of the whole sample) are identified as AGNs through common optical diagnostics. We model the spectral energy distributions of our sample and found that all require a strong AGN component, with an average intrinsic AGN fraction at 8 mu m of 0.91. Additionally, the fits require large extinction coefficients with an average E(B - V)(AGN) = 17.8 (average A(V)(AGN) = 53.4). By focusing on the area outside traditional mid-IR photometric cuts, we are able to capture and characterize a population of deeply buried quasars that were previously unattainable through X-ray surveys alone.
VersionFinal published version
SponsorsJames O. Freedman Presidential Scholars Program; Dartmouth E.E. Just Program; National Science Foundation ; Faculty Early Career Development Program ; National Aeronautics and Space Administration [NNX16AN48G, NNX15AP24G]; National Aeronautics and Space Administration; Alfred P. Sloan Foundation; National Science Foundation; U.S. Department of Energy Office of Science