Journal
ASTROPHYSICAL JOURNAL
Volume 776, Issue 2, Pages -Publisher
IOP PUBLISHING LTD
DOI: 10.1088/0004-637X/776/2/136
Keywords
galaxies: halos; quasars: absorption lines
Categories
Funding
- Alexander von Humboldt foundation
- German Federal Ministry for Education and Research
- National Science Foundation (NSF) [AST-1010004, AST-0407448, AST-0909182, AST-1109288]
- Ajax Foundation
- W. M. Keck Foundation
- AURA through the NSF [AST 01-32798]
- Alfred P. Sloan Foundation
- National Science Foundation
- U.S. Department of Energy
- National Aeronautics and Space Administration
- Japanese Monbukagakusho
- Max Planck Society
- Higher Education Funding Council for England
- American Museum of Natural History
- Astrophysical Institute Potsdam
- University of Basel
- University of Cambridge
- Case Western Reserve University
- University of Chicago
- Drexel University
- Fermilab
- Institute for Advanced Study
- Japan Participation Group
- Johns Hopkins University
- Joint Institute for Nuclear Astrophysics
- Kavli Institute for Particle Astrophysics and Cosmology
- Korean Scientist Group
- Chinese Academy of Sciences (LAMOST)
- Los Alamos National Laboratory
- Max-Planck Institute for Astronomy (MPIA)
- Max-Planck-Institute for Astrophysics (MPA)
- New Mexico State University
- Ohio State University
- University of Pittsburgh
- University of Portsmouth
- Princeton University
- United States Naval Observatory
- University of Washington
- University of Arizona
- Brazilian Participation Group
- Brookhaven National Laboratory
- Carnegie Mellon University
- University of Florida
- French Participation Group
- German Participation Group
- Harvard University
- Instituto de Astrofisica de Canarias
- Michigan State/Notre Dame/JINA Participation Group
- Lawrence Berkeley National Laboratory
- Max Planck Institute for Astrophysics
- Max Planck Institute for Extraterrestrial Physics
- New York University
- Pennsylvania State University
- Spanish Participation Group
- University of Tokyo
- University of Utah
- Vanderbilt University
- University of Virginia
- Yale University
- Direct For Mathematical & Physical Scien
- Division Of Astronomical Sciences [1010004] Funding Source: National Science Foundation
- Direct For Mathematical & Physical Scien
- Division Of Astronomical Sciences [1313422] Funding Source: National Science Foundation
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With close pairs of quasars at different redshifts, a background quasar sightline can be used to study a foreground quasar's environment in absorption. We use a sample of 650 projected quasar pairs to study the H I Ly alpha absorption transverse to luminous, z similar to 2 quasars at proper separations of 30 kpc < R-perpendicular to < 1 Mpc. In contrast to measurements along the line-of-sight, regions transverse to quasars exhibit enhanced H I Ly alpha absorption and a larger variance than the ambient intergalactic medium, with increasing absorption and variance toward smaller scales. Analysis of composite spectra reveals excess absorption characterized by a Ly alpha equivalent width profile W = 2.3 angstrom (R-perpendicular to/100 kpc)(-0.46). We also observe a high (similar or equal to 60%) covering factor of strong, optically thick H I absorbers (H I column N-H I > 10(17.3) cm(-2)) at separations R-perpendicular to < 200 kpc, which decreases to similar to 20% at R-perpendicular to similar or equal to 1Mpc, but still represents a significant excess over the cosmic average. This excess of optically thick absorption can be described by a quasar-absorber cross-correlation function xi(QA)(r) = (r/r(0))(gamma) with a large correlation length r(0) = 12.5(-1.4)(+2.7) h(-1) Mpc (comoving) and gamma = 1.68(-0.30)(+0.14). The H I absorption measured around quasars exceeds that of any previously studied population, consistent with quasars being hosted by massive dark matter halos M-halo approximate to 10(12.5) M-circle dot at z similar to 2.5. The environments of these massive halos are highly biased toward producing optically thick gas, and may even dominate the cosmic abundance of Lyman limit systems and hence the intergalactic opacity to ionizing photons at z similar to 2.5. The anisotropic absorption around quasars implies the transverse direction is much less likely to be illuminated by ionizing radiation than the line-of-sight.
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