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Paper: X-rays from the Dawn of the Modern Universe: Chandra and SMM-Newton Observations of z > 4 Quasars
Volume: 311, AGN Physics with the Sloan Digital Sky Survey
Page: 317
Authors: Vignali, C.; Brandt, W.N.; Schneider, D.P.
Abstract: Quasars at z > 4 provide direct information on the first massive structures to form in the Universe. Recent ground-based optical surveys (e.g., the Sloan Digital Sky Survey) have discovered large numbers of high-redshift quasars, increasing the number of known quasars at z > 4 to ≈ 500. Most of these quasars are suitable for follow-up X-ray studies. Here we review X-ray studies of the highest redshift quasars, focusing on recent advances enabled largely by the capabilities of Chandra and XMM-Newton. Overall, analyses indicate that the X-ray emission and broad-band properties of high-redshift and local quasars are reasonably similar, once luminosity effects are taken into account. Thus, despite the strong changes in large-scale environment and quasar number density that have occurred from z ≈ 0−6, individual quasar X-ray emission regions appear to evolve relatively little.
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