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The X-ray variability of high-redshift QSOs
Authors:JManners  OAlmaini  ALawrence
Institution:Institute for Astronomy, University of Edinburgh, Royal Observatory, Blackford Hill, Edinburgh EH9 3HJ
Abstract: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  0.12)  in the sense that QSOs of the same X-ray luminosity are more variable at  z>2  . We discuss possible explanations for this effect. The simplest explanation may be that high-redshift QSOs are accreting at a larger fraction of the Eddington limit than local AGNs.
Keywords:galaxies: active  galaxies: evolution  galaxies: nuclei  quasars: general  X-rays: galaxies  X-rays: general
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