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2008ApJ...685..773G - Astrophys. J., 685, 773-786 (2008/October-1)

Are optically selected quasars universally X-ray luminous? X-ray-UV relations in Sloan Digital Sky Survey quasars.

GIBSON R.R., BRANDT W.N. and SCHNEIDER D.P.

Abstract (from CDS):

We analyze archived Chandra and XMM-Newton X-ray observations of 536 Sloan Digital Sky Survey (SDSS) Data Release 5 (DR5) quasars (QSOs) at 1.7≤z≤2.7 in order to characterize the relative UV and X-ray spectral properties of QSOs that do not have broad UV absorption lines (BALs). We constrain the fraction of X-ray-weak, non-BAL QSOs and find that such objects are rare; for example, sources underluminous by a factor of 10 comprise ≲2% of optically selected SDSS QSOs. X-ray luminosities vary with respect to UV emission by a factor of ≲2 over several years for most sources. UV continuum reddening and the presence of narrow-line absorbing systems are not strongly associated with X-ray weakness in our sample. X-ray brightness is significantly correlated with UV emission-line properties, so that relatively X-ray-weak, non-BAL QSOs generally have weaker, blueshifted C IV λ1549 emission and broader C III] λ1909 lines. The C IV emission-line strength depends on both UV and X-ray luminosity, suggesting that the physical mechanism driving the global Baldwin effect is also associated with X-ray emission.

Abstract Copyright:

Journal keyword(s): Galaxies: Active - Galaxies: Nuclei - Galaxies: Quasars: Absorption Lines - Galaxies: Quasars: Emission Lines - X-Rays: General

VizieR on-line data: <Available at CDS (J/ApJ/685/773): table1.dat table2.dat>

Simbad objects: 546

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2020.10.20-20:54:13

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