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X-ray emission from the most luminous z>4 Palomar Digital Sky Survey Quasars: the Chandra view

C. Vignali·W. N. Brandt·D. P. Schneider·G. P. Garmire·S. Kaspi
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Abstract

We present the results obtained from exploratory Chandra observations of nine high-redshift (z=4.09-4.51) quasars, selected from among the optically brightest Palomar Digital Sky Survey quasars known. Their broad-band spectral energy distributions are characterized, on average, by steeper alpha_ox values ( =-1.81+/-0.03) than those of lower-redshift, lower-luminosity samples of quasars. We find a significant correlation between AB1450(1+z) magnitude and soft X-ray flux, suggesting that the engine powering the UV and X-ray emission is the same. The joint 2-30 keV rest-frame X-ray spectrum is well parameterized by a Gamma=2.0+/-0.2 power-law model with no evidence for intrinsic absorption (N_H<8.8 10^{21} cm^-2).

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C. Vignali, W. N. Brandt, D. P. Schneider, G. P. Garmire, S. Kaspi. 2002-09-30. X-ray emission from the most luminous z>4 Palomar Digital Sky Survey Quasars: the Chandra view. https://arxiv.org/abs/astro-ph/0210001

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