Composite Spectral Energy Distributions and Infrared–Optical Colors of Type 1 and Type 2 Quasars
AuthorHickox, Ryan C.
Myers, Adam D.
Greene, Jenny E.
Hainline, Kevin N.
DiPompeo, Michael A.
AffiliationUniv Arizona, Steward Observ
MetadataShow full item record
PublisherIOP PUBLISHING LTD
CitationComposite Spectral Energy Distributions and Infrared–Optical Colors of Type 1 and Type 2 Quasars 2017, 849 (1):53 The Astrophysical Journal
JournalThe Astrophysical Journal
Rights© 2017. The American Astronomical Society. All rights reserved.
Collection InformationThis item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at email@example.com.
AbstractWe present observed mid-infrared and optical colors and composite spectral energy distributions (SEDs) of type 1 (broad-line) and 2 (narrow-line) quasars selected from Sloan Digital Sky Survey (SDSS) spectroscopy. A significant fraction of powerful quasars are obscured by dust and are difficult to detect in optical photometric or spectroscopic surveys. However, these may be more easily identified on the basis of mid-infrared (MIR) colors and SEDs. Using samples of SDSS type 1 and 2 matched in redshift and [O III] luminosity, we produce composite rest-frame 0.2-15 mu m SEDs based on SDSS, UKIDSS, and Wide-field Infrared Survey Explorer photometry and perform model fits using simple galaxy and quasar SED templates. The SEDs of type 1 and 2 quasars are remarkably similar, with the differences explained primarily by the extinction of the quasar component in the type 2 systems. For both types of quasar, the flux of the active galactic nucleus (AGN) relative to the host galaxy increases with AGN luminosity (L-[O III]) and redder observed MIR color, but we find only weak dependencies of the composite SEDs on mechanical jet power as determined through radio luminosity. We conclude that luminous quasars can be effectively selected using simple MIR color criteria similar to those identified previously (W1-W2 > 0.7; Vega), although these criteria miss many heavily obscured objects. Obscured quasars can be further identified based on optical-IR colors (for example, (u-W3[AB])> 1.4(W1-W2[Vega])+ 3.2). These results illustrate the power of large statistical studies of obscured quasars selected on the basis of MIR and optical photometry.
VersionFinal published version
SponsorsNational Science Foundation through AST [1211112, 1515404]; CAREER ; NASA [NNX16AN48G, NNX15AU32H, NNX12AE38G, NNX15AP24G]; Alfred P. Sloan Research Fellowship; National Aeronautics and Space Administration; National Science Foundation; Alfred P. Sloan Foundation; U.S. Department of Energy Office of Science