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Title:
A Census of Intrinsic Narrow Absorption Lines in the Spectra of Quasars at z = 2-4
Authors:
Misawa, Toru; Charlton, Jane C.; Eracleous, Michael; Ganguly, Rajib; Tytler, David; Kirkman, David; Suzuki, Nao; Lubin, Dan
Affiliation:
AA(Department of Astronomy and Astrophysics, Pennsylvania State University, University Park, PA 16802.), AB(Department of Astronomy and Astrophysics, Pennsylvania State University, University Park, PA 16802.), AC(Department of Astronomy and Astrophysics, Pennsylvania State University, University Park, PA 16802.; Center for Gravitational Wave Physics, Pennsylvania State University, University Park, PA 16802.), AD(Department of Physics and Astronomy, University of Wyoming, Laramie, WY 82071.), AE(Center for Astrophysics and Space Sciences, University of California at San Diego, La Jolla, CA 92093-0424.; Visiting Astronomer, W. M. Keck Observatory, which is a joint facility of the University of California, the California Institute of Technology, and NASA.), AF(Center for Astrophysics and Space Sciences, University of California at San Diego, La Jolla, CA 92093-0424.; Visiting Astronomer, W. M. Keck Observatory, which is a joint facility of the University of California, the California Institute of Technology, and NASA.), AG(Center for Astrophysics and Space Sciences, University of California at San Diego, La Jolla, CA 92093-0424.; Visiting Astronomer, W. M. Keck Observatory, which is a joint facility of the University of California, the California Institute of Technology, and NASA.), AH(Center for Astrophysics and Space Sciences, University of California at San Diego, La Jolla, CA 92093-0424.; Visiting Astronomer, W. M. Keck Observatory, which is a joint facility of the University of California, the California Institute of Technology, and NASA.)
Publication:
The Astrophysical Journal Supplement Series, Volume 171, Issue 1, pp. 1-28. (ApJS Homepage)
Publication Date:
07/2007
Origin:
UCP
ApJ Keywords:
Accretion, Accretion Disks, Galaxies: Active, Galaxies: Quasars: Absorption Lines, Galaxies: Quasars: General
DOI:
10.1086/513713
Bibliographic Code:
2007ApJS..171....1M

Abstract

We use Keck HIRES spectra of 37 optically bright quasars at z=2-4 to study narrow absorption lines that are intrinsic to the quasars (intrinsic NALs, produced in gas that is physically associated with the quasar central engine). We identify 150 NAL systems, which contain 124 C IV, 12 N V, and 50 Si IV doublets, of which 18 are associated systems (within 5000 km s-1 of the quasar redshift). We use partial coverage analysis to separate intrinsic NALs from NALs produced in cosmologically intervening structures. We find 39 candidate intrinsic systems (28 reliable determinations and 11 that are possibly intrinsic). We estimate that 10%-17% of C IV systems at blueshifts of 5000-70,000 km s-1 relative to quasars are intrinsic. At least 32% of quasars contain one or more intrinsic C IV NALs. Considering N V and Si IV doublets showing partial coverage as well, at least 50% of quasars host intrinsic NALs. This result constrains the solid angle subtended by the absorbers to the background source(s). We identify two families of intrinsic NAL systems, those with strong N V absorption and those with negligible absorption in N V but with partial coverage in the C IV doublet. We discuss the idea that these two families represent different regions or conditions in accretion disk winds. Of the 26 intrinsic C IV NAL systems, 13 have detectable low-ionization absorption lines at similar velocities, suggesting that these are two-phase structures in the wind rather than absorbers in the host galaxy. We also compare possible models for quasar outflows, including radiatively accelerated disk-driven winds, magnetocentrifugally accelerated winds, and pressure-driven winds, and we discuss ways of distinguishing between these models observationally.

The data presented here were obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California, and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W. M. Keck Foundation.


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