Journal article
C IV emission-line properties and systematic trends in quasar black hole mass estimates
Monthly notices of the Royal Astronomical Society, v 461(1), pp 647-665
01 Sep 2016
Abstract
Black hole masses are crucial to understanding the physics of the connection between quasars and their host galaxies and measuring cosmic black hole-growth. At high redshift, z greater than or similar to 2.1, black holemasses are normally derived using the velocity width of the C IV lambda lambda 1548, 1550 broad emission line, based on the assumption that the observed velocity widths arise from virial-induced motions. Inmany quasars, the C IV emission line exhibits significant blue asymmetries ('blueshifts') with the line centroid displaced by up to thousands of km s(-1) to the blue. These blueshifts almost certainly signal the presence of strong outflows, most likely originating in a disc wind. We have obtained near-infrared spectra, including the H alpha lambda 6565 emission line, for 19 luminous (L-Bol = 46.5-47.5 erg s(-1)) Sloan Digital Sky Survey quasars, at redshifts 2 < z < 2.7, with C IV emission lines spanning the full range of blueshifts present in the population. A strong correlation between C IV velocity width and blueshift is found and, at large blueshifts, > 2000 km s(-1), the velocity widths appear to be dominated by non-virial motions. Black hole masses, based on the full width at half-maximum of the C IV emission line, can be overestimated by a factor of 5 at large blueshifts. A larger sample of quasar spectra with both C IV and H beta, or H alpha, emission lines will allow quantitative corrections to C IV-based black hole masses as a function of blueshift to be derived. We find that quasars with large C IV blueshifts possess high Eddington luminosity ratios and that the fraction of high-blueshift quasars in a flux-limited sample is enhanced by a factor of approximately 4 relative to a sample limited by black hole mass.
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Details
- Title
- C IV emission-line properties and systematic trends in quasar black hole mass estimates
- Creators
- Liam Coatman - Institute of AstronomyPaul C. Hewett - Institute of AstronomyManda Banerji - Institute of AstronomyGordon T. Richards - Drexel University
- Publication Details
- Monthly notices of the Royal Astronomical Society, v 461(1), pp 647-665
- Publisher
- Oxford Univ Press
- Number of pages
- 19
- Grant note
- Max Planck Society; Foundation CELLEX University of Cambridge University of Chicago Max-Planck-Institute for Astrophysics (MPA) National Aeronautics and Space Administration; National Aeronautics & Space Administration (NASA) Korean Scientist Group Institute for Advanced Study Chinese Academy of Sciences (LAMOST); Chinese Academy of Sciences United States Naval Observatory Japanese Monbukagakusho; Ministry of Education, Culture, Sports, Science and Technology, Japan (MEXT) Ohio State University Fermilab University of Pittsburgh Los Alamos National Laboratory; United States Department of Energy (DOE) University of Basel STFC; UK Research & Innovation (UKRI); Science & Technology Facilities Council (STFC) Joint Institute for Nuclear Astrophysics Alfred P. Sloan Foundation University of Washington Princeton University US Department of Energy; United States Department of Energy (DOE) Max-Planck-Institute for Astronomy (MPIA) New Mexico State University Japan Participation Group; Sloan Digital Sky Survey (SDSS) University of Portsmouth Higher Education Funding Council for England; UK Research & Innovation (UKRI); Higher Education Funding Council for England (HEFCE) Astrophysical Institute Potsdam Kavli Institute for Particle Astrophysics and Cosmology American Museum of Natural History Case Western Reserve University STFC via an Ernest Rutherford Fellowship; UK Research & Innovation (UKRI); Science & Technology Facilities Council (STFC) National Science Foundation; National Science Foundation (NSF) Science and Technology Facilities Council (STFC); UK Research & Innovation (UKRI); Science & Technology Facilities Council (STFC); Science and Technology Development Fund (STDF) Johns Hopkins University Drexel University ST/M005305/1; ST/L001381/1 / STFC; UK Research & Innovation (UKRI); Science & Technology Facilities Council (STFC)
- Resource Type
- Journal article
- Language
- English
- Academic Unit
- Physics
- Web of Science ID
- WOS:000383272500049
- Scopus ID
- 2-s2.0-84988835926
- Other Identifier
- 991019169568104721
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- Collaboration types
- Domestic collaboration
- International collaboration
- Web of Science research areas
- Astronomy & Astrophysics