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Title:
A Full Year's Chandra Exposure on Sloan Digital Sky Survey Quasars from the Chandra Multiwavelength Project
Authors:
Green, Paul J.; Aldcroft, T. L.; Richards, G. T.; Barkhouse, W. A.; Constantin, A.; Haggard, D.; Karovska, M.; Kim, D.-W.; Kim, M.; Vikhlinin, A.; Anderson, S. F.; Mossman, A.; Kashyap, V.; Myers, A. C.; Silverman, J. D.; Wilkes, B. J.; Tananbaum, H.
Affiliation:
AA(Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138, USA ; Visiting Astronomer, Kitt Peak National Observatory, Cerro Tololo Inter-American Observatory, and National Optical Astronomy Observatory, which is operated by the Association of Universities for Research in Astronomy, Inc. (AURA), under cooperative agreement with the National Science Foundation.; ), AB(Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138, USA ), AC(Department of Physics, Drexel University, 3141 Chestnut Street, Philadelphia, PA 15260, USA ), AD(Department of Physics, University of North Dakota, Grand Forks, ND 58202, USA ; Visiting Astronomer, Kitt Peak National Observatory, Cerro Tololo Inter-American Observatory, and National Optical Astronomy Observatory, which is operated by the Association of Universities for Research in Astronomy, Inc. (AURA), under cooperative agreement with the National Science Foundation.), AE(Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138, USA ), AF(Department of Astronomy, University of Washington, Seattle, WA, USA ), AG(Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138, USA ), AH(Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138, USA ), AI(International Center for Astrophysics, Korea Astronomy and Space Science Institute, Daejeon, 305-348, Korea ), AJ(Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138, USA ), AK(Department of Astronomy, University of Washington, Seattle, WA, USA ), AL(Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138, USA ), AM(Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138, USA ), AN(Department of Astronomy, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA ), AO(Institute for Astronomy, ETH Zürich, 8093 Zürich, Switzerland ), AP(Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138, USA ), AQ(Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138, USA )
Publication:
The Astrophysical Journal, Volume 690, Issue 1, pp. 644-669 (2009). (ApJ Homepage)
Publication Date:
01/2009
Origin:
IOP
ApJ Keywords:
galaxies: active, quasars: absorption lines, quasars: general, surveys, X-rays: general
DOI:
10.1088/0004-637X/690/1/644
Bibliographic Code:
2009ApJ...690..644G

Abstract

We study the spectral energy distributions and evolution of a large sample of optically selected quasars from the Sloan Digital Sky Survey that were observed in 323 Chandra images analyzed by the Chandra Multiwavelength Project. Our highest-confidence matched sample includes 1135 X-ray detected quasars in the redshift range 0.2 < z < 5.4, representing some 36 Msec of effective exposure. We provide catalogs of QSO properties, and describe our novel method of calculating X-ray flux upper limits and effective sky coverage. Spectroscopic redshifts are available for about 1/3 of the detected sample; elsewhere, redshifts are estimated photometrically. We detect 56 QSOs with redshift z > 3, substantially expanding the known sample. We find no evidence for evolution out to z ~ 5 for either the X-ray photon index Γ or for the ratio of optical/UV to X-ray flux αox. About 10% of detected QSOs show best-fit intrinsic absorbing columns greater than 1022 cm-2, but the fraction might reach ~1/3 if most nondetections are absorbed. We confirm a significant correlation between αox and optical luminosity, but it flattens or disappears for fainter (MB gsim -23) active galactic nucleus (AGN) alone. We report significant hardening of Γ both toward higher X-ray luminosity, and for relatively X-ray loud quasars. These trends may represent a relative increase in nonthermal X-ray emission, and our findings thereby strengthen analogies between Galactic black hole binaries and AGN. For uniformly selected subsamples of narrow-line Seyfert 1s and narrow absorption line QSOs, we find no evidence for unusual distributions of either αox or Γ.
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