TY - JOUR
T1 - Extremely red quasars in BOSS
AU - Hamann, Fred
AU - Zakamska, Nadia L.
AU - Ross, Nicholas
AU - Paris, Isabelle
AU - Alexandroff, Rachael M.
AU - Villforth, Carolin
AU - Richards, Gordon T.
AU - Herbst, Hanna
AU - Niel Brandt, W.
AU - Cook, Ben
AU - Denney, Kelly D.
AU - Greene, Jenny E.
AU - Schneider, Donald P.
AU - Strauss, Michael A.
N1 - Funding Information:
We are grateful to A. Baskin, D. M. Crenshaw, G. J. Ferland, S. B. Kraemer, and A. Laor for helpful conversations. FH acknowledges support from the USA National Science Foundation grant AST-1009628. KDD is supported by an NSF Astronomy & Astrophysics Postdoctoral Fellowship awarded under NSF grant AST-1302093. Funding for SDSS-III was 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 website 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, University of Cambridge, 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.
Publisher Copyright:
© 2016 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society
PY - 2017/1/1
Y1 - 2017/1/1
N2 - Red quasars are candidate young objects in an early transition stage of massive galaxy evolution. Our team recently discovered a population of extremely red quasars (ERQs) in the Baryon Oscillation Spectroscopic Survey (BOSS) that has a suite of peculiar emission-line properties including large rest equivalent widths (REWs), unusual 'wingless' line profiles, large N V/Lyα, N V/C IV, Si IV/C IV and other flux ratios, and very broad and blueshifted [O III] λ5007. Here we present a new catalogue of C IV and N V emission-line data for 216 188 BOSS quasars to characterize the ERQ line properties further. We show that they depend sharply on UV-to-mid-IR colour, secondarily on REW(C IV), and not at all on luminosity or the Baldwin Effect. We identify a 'core' sample of 97 ERQs with nearly uniform peculiar properties selected via i-W3 ≥ 4.6 (AB) and REW(C IV) ≥ 100 Å at redshifts 2.0-3.4. A broader search finds 235 more red quasars with similar unusual characteristics. The core ERQs have median luminosity (log L(ergs s−1) ∼ 47.1, sky density 0.010 deg−2, surprisingly flat/blue UV spectra given their red UV-to-mid-IR colours, and common outflow signatures including BALs or BAL-like features and large C IV emission-line blueshifts. Their SEDs and line properties are inconsistent with normal quasars behind a dust reddening screen. We argue that the core ERQs are a unique obscured quasar population with extreme physical conditions related to powerful outflows across the line-forming regions. Patchy obscuration by small dusty clouds could produce the observed UV extinctions without substantial UV reddening.
AB - Red quasars are candidate young objects in an early transition stage of massive galaxy evolution. Our team recently discovered a population of extremely red quasars (ERQs) in the Baryon Oscillation Spectroscopic Survey (BOSS) that has a suite of peculiar emission-line properties including large rest equivalent widths (REWs), unusual 'wingless' line profiles, large N V/Lyα, N V/C IV, Si IV/C IV and other flux ratios, and very broad and blueshifted [O III] λ5007. Here we present a new catalogue of C IV and N V emission-line data for 216 188 BOSS quasars to characterize the ERQ line properties further. We show that they depend sharply on UV-to-mid-IR colour, secondarily on REW(C IV), and not at all on luminosity or the Baldwin Effect. We identify a 'core' sample of 97 ERQs with nearly uniform peculiar properties selected via i-W3 ≥ 4.6 (AB) and REW(C IV) ≥ 100 Å at redshifts 2.0-3.4. A broader search finds 235 more red quasars with similar unusual characteristics. The core ERQs have median luminosity (log L(ergs s−1) ∼ 47.1, sky density 0.010 deg−2, surprisingly flat/blue UV spectra given their red UV-to-mid-IR colours, and common outflow signatures including BALs or BAL-like features and large C IV emission-line blueshifts. Their SEDs and line properties are inconsistent with normal quasars behind a dust reddening screen. We argue that the core ERQs are a unique obscured quasar population with extreme physical conditions related to powerful outflows across the line-forming regions. Patchy obscuration by small dusty clouds could produce the observed UV extinctions without substantial UV reddening.
KW - Galaxies: active
KW - Quasars: absorption lines
KW - Quasars: emission lines
KW - Quasars: general
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U2 - 10.1093/mnras/stw2387
DO - 10.1093/mnras/stw2387
M3 - Article
AN - SCOPUS:85014151377
SN - 0035-8711
VL - 464
SP - 3431
EP - 3463
JO - Monthly Notices of the Royal Astronomical Society
JF - Monthly Notices of the Royal Astronomical Society
IS - 3
ER -