Journal article
Chandra Observations of the Highest Redshift Quasars from the Sloan Digital Sky Survey
The Astrophysical journal, v 644(1)
20 Feb 2006
Abstract
Astrophys.J. 644 (2006) 86-99 We present new Chandra observations of 21 z>4 quasars, including 11 sources
at z>5. These observations double the number of X-ray detected quasars at z>5,
allowing investigation of the X-ray spectral properties of a substantial sample
of quasars at the dawn of the modern Universe. By jointly fitting the spectra
of 15 z>5 radio-quiet quasars (RQQs), including sources from the Chandra
archive, with a total of 185 photons, we find a mean X-ray power-law photon
index of Gamma=1.95^{+0.30}_{-0.26}, and a mean neutral intrinsic absorption
column density of N_H<~6x10^{22} cm^{-2}. These results show that quasar X-ray
spectral properties have not evolved up to the highest observable redshifts. We
also find that the mean optical-X-ray spectral slope (alpha_ox) of
optically-selected z>5 RQQs, excluding broad absorption line quasars, is
alpha_ox=-1.69+/-0.03, which is consistent with the value predicted from the
observed relationship between alpha_ox and ultraviolet luminosity. Four of the
sources in our sample are members of the rare class of weak emission-line
quasars, and we detect two of them in X-rays. We discuss the implications our
X-ray observations have for the nature of these mysterious sources and, in
particular, whether their weak-line spectra are a consequence of continuum
boosting or a deficit of high-ionization line emitting gas.
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Details
- Title
- Chandra Observations of the Highest Redshift Quasars from the Sloan Digital Sky Survey
- Creators
- Ohad Shemmer - Pennsylvania State UniversityW. N Brandt - Pennsylvania State UniversityDonald P Schneider - Pennsylvania State UniversityXiaohui Fan - Steward Health Care SystemMichael A Strauss - Princeton UniversityAleksandar M Diamond-Stanic - Steward Health Care SystemGordon T Richards - Princeton UniversityScott F Anderson - University of WashingtonJames E Gunn - Princeton UniversityJon Brinkmann - Apache Corporation
- Publication Details
- The Astrophysical journal, v 644(1)
- Resource Type
- Journal article
- Language
- English
- Academic Unit
- Physics
- Web of Science ID
- WOS:000238339200008
- Scopus ID
- 2-s2.0-33747052848
- Other Identifier
- 991019201386504721
InCites Highlights
Data related to this publication, from InCites Benchmarking & Analytics tool:
- Collaboration types
- Domestic collaboration
- Web of Science research areas
- Astronomy & Astrophysics