SIMBAD references

2006AJ....131..659M - Astron. J., 131, 659-665 (2006/February-0)

Chandra observations of six QSOs at z ~ 3.


Abstract (from CDS):

We report the results of our Chandra observations of six QSOs at z∼3 from the Palomer Transit Grism Survey. Our primary goal is to investigate the possible systematic change of αox between z>4 and z∼3, between which a rapid rise of luminous QSO number density with cosmic time is observed. The summed spectrum showed a power-law spectrum with a photon index of Γ~1.9, which is similar to other unabsorbed active galactic nuclei. Combining our z∼3 QSOs with X-ray observations of QSOs at z>4 from literature or archives, we find a correlation of αox with optical luminosity. This is consistent with the fact that the luminosity function slope of the luminous end of the X-ray-selected QSOs is steeper than that of optically selected QSOs. We discuss an upper limit to the redshift dependence of αox using a Monte Carlo simulation. Within the current statistical errors, including the derived limits on the redshift dependence of αox, we found that the behaviors of the X-ray and optically selected QSO number densities are consistent with each other.

Abstract Copyright:

Journal keyword(s): Galaxies: Active - Galaxies: High-Redshift - Galaxies: Luminosity Function, Mass Function - Galaxies: Quasars: General - X-Rays: Galaxies

CDS comments: Par. 3, SDSS 1605-0122 is a misprint for 0112 (QSO J1605-0112)

Simbad objects: 8

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