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The X-ray Variability of High-Redshift QSOs

Published online by Cambridge University Press:  12 April 2016

J. Manners ,
O. Almaini  and
A. Lawrence
J. Manners
Affiliation:
Institute for Astronomy, University of Edinburgh, Royal Observatory, Blackford Hill, Edinburgh EH9 3HJ
O. Almaini
Affiliation:
Institute for Astronomy, University of Edinburgh, Royal Observatory, Blackford Hill, Edinburgh EH9 3HJ
A. Lawrence
Affiliation:
Institute for Astronomy, University of Edinburgh, Royal Observatory, Blackford Hill, Edinburgh EH9 3HJ

Abstract

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We present an analysis of X-ray variability in a sample of 156 radio quiet quasars taken from the ROSAT archive, covering a redshift range 0.1 < z < 4.1. Through combining light curves in ensembles we are able to identify trends in variability amplitude with luminosity and with redshift. The decline in variability amplitude with luminosity identified in local AGN (z < 0.1) is confirmed out to z = 2. There is tentative evidence for an increase in QSO X-ray variability amplitude towards high redshifts (z > 2) in the sense that QSOs of the same X-ray luminosity are more variable at z > 2. The simplest explanation for this effect may be that high-redshift QSOs are accreting at a higher efficiency than local AGN.

Type
Part 3. X-ray Surveys for AGN
Information
International Astronomical Union Colloquium , Volume 184: AGN Surveys , 2002 , pp. 251 - 256
Copyright
Copyright © Astronomical Society of the Pacific 2002

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