Low accretion rates at the AGN cosmic downsizing epoch
نویسندگان
چکیده
Context. X-ray surveys of Active Galactic Nuclei (AGN) indicate “cosmic downsizing”, with the comoving number density of highluminosity objects peaking at higher redshifts (z ∼ 2) than low-luminosity AGN (z < 1). Aims. We test whether downsizing is caused by activity shifting towards low-mass black holes accreting at near-Eddington rates, or by a change in the average rate of accretion onto supermassive black holes. We estimate the black hole masses and Eddington ratios of an X-ray selected sample of AGN in the Chandra Deep Field South at z < 1, probing the epoch where AGN cosmic downsizing
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تاریخ انتشار 2007