Journal article
Extremely red quasars from SDSS, BOSS and WISE: classification of optical spectra
Monthly notices of the Royal Astronomical Society, v 453(4), pp 3932-3952
11 Nov 2015
Abstract
Quasars with extremely red infrared-to-optical colours are an interesting population that can test ideas about quasar evolution as well as orientation, obscuration and geometric effects in the so-called AGN unified model. To identify such a population, we match the quasar catalogues of the Sloan Digital Sky Survey (SDSS), the Baryon Oscillation Spectroscopic Survey (BOSS) to the Wide-Field Infrared Survey Explorer (WISE) to identify quasars with extremely high infrared-to-optical ratios. We identify 65 objects with r(AB) -W4(Vega) > 14 mag (i. e. F-v (22 mu m)/F-v (r) greater than or similar to 1000). This sample spans a redshift range of 0.28 < z < 4.36 and has a bimodal distribution, with peaks at z similar to 0.8 and z similar to 2.5. It includes three z > 2.6 objects that are detected in the W4 band but not W1 or W2 (i. e. 'W1W2 dropouts'). The SDSS/BOSS spectra show that the majority of the objects are reddened type 1 quasars, type 2 quasars (both at low and high redshift) or objects with deep low-ionization broad absorption lines (BALs) that suppress the observed r-band flux. In addition, we identify a class of type 1 permitted broad emission-line objects at z similar or equal to 2-3 which are characterized by emission line rest-frame equivalent widths (REWs) of greater than or similar to 150 angstrom, much larger than those of typical quasars. In particular, 55 per cent (45 per cent) of the non-BAL type 1s with measurable CIV in our sample have REW(C IV) > 100 (150)angstrom, compared to only 5.8 per cent (1.3 per cent) for non-BAL quasars in BOSS. These objects often also have unusual line ratios, such as very high NV/Ly alpha ratios. These large REWs might be caused by suppressed continuum emission analogous to type 2 quasars; however, there is no obvious mechanism in standard unified models to suppress the continuum without also obscuring the broad emission lines.
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Details
- Title
- Extremely red quasars from SDSS, BOSS and WISE: classification of optical spectra
- Creators
- Nicholas P. Ross - Drexel UniversityFred Hamann - University of Florida HealthNadia L. Zakamska - Johns Hopkins UniversityGordon T. Richards - Drexel UniversityCarolin Villforth - University of Florida HealthMichael A. Strauss - Princeton UniversityJenny E. Greene - Princeton UniversityRachael Alexandroff - Johns Hopkins UniversityW. Niel Brandt - Pennsylvania State UniversityGuilin Liu - Johns Hopkins UniversityAdam D. Myers - Max Planck Institute for AstronomyIsabelle Paris - Trieste Astronomical ObservatoryDonald P. Schneider - Pennsylvania State University
- Publication Details
- Monthly notices of the Royal Astronomical Society, v 453(4), pp 3932-3952
- Publisher
- Oxford Univ Press
- Number of pages
- 21
- Grant note
- University of Tokyo New York University Spanish Participation Group University of Cambridge University of Utah University of Florida U.S. Department of Energy; United States Department of Energy (DOE) National Aeronautics and Space Administration; National Aeronautics & Space Administration (NASA) Lawrence Berkeley National Laboratory; United States Department of Energy (DOE) AST-1009628 / USA National Science Foundation; National Science Foundation (NSF) Ohio State University Vanderbilt University Alfred P. Sloan Foundation University of Washington German Participation Group Instituto de Astrofisica de Canarias Princeton University NASA; National Aeronautics & Space Administration (NASA) HST-GO-13014.06 / Hubble grant University of Arizona Yale University New Mexico State University Pennsylvania State University Brookhaven National Laboratory; United States Department of Energy (DOE) University of Portsmouth Brazilian Participation Group ST/L00481X/1 / STFC; UK Research & Innovation (UKRI); Science & Technology Facilities Council (STFC) French Participation Group ST/L00481X/1 / Science and Technology Facilities Council; UK Research & Innovation (UKRI); Science & Technology Facilities Council (STFC) Michigan State/Notre Dame/JINA Participation Group University of Virginia National Science Foundation; National Science Foundation (NSF) Max Planck Institute for Astrophysics Johns Hopkins University
- Resource Type
- Journal article
- Language
- English
- Academic Unit
- Physics
- Web of Science ID
- WOS:000363651600044
- Scopus ID
- 2-s2.0-84961668720
- Other Identifier
- 991019169528004721
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- Collaboration types
- Domestic collaboration
- International collaboration
- Web of Science research areas
- Astronomy & Astrophysics