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A Full Year's Chandra Exposure on Sloan Digital Sky Survey Quasars From the Chandra Multiwavelength Project
The Astrophysical journal, Vol.690(1), pp.644-669
IOP Publishing
01 Jan 2008
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 −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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Details
- Title
- A Full Year's Chandra Exposure on Sloan Digital Sky Survey Quasars From the Chandra Multiwavelength Project
- Creators
- Paul J GreenThomas L AldcroftG. T RichardsW. A BarkhouseAna-Maria ConstantinD HaggardMargarita Karovska NeilyD. -W KimM KimAlexey A VikhlininS. F AndersonAmy E MossmanVinay L KashyapA. C MyersJ. D SilvermanBelinda Jane WilkesHarvey D Tananbaum
- Publication Details
- The Astrophysical journal, Vol.690(1), pp.644-669
- Publisher
- IOP Publishing
- Resource Type
- Other
- Language
- English
- Academic Unit
- Physics
- Identifiers
- 991014878532704721
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- Astronomy & Astrophysics