Optical Identification of the ASCA Large Sky Survey
Abstract
We present results of optical identification of the X-ray sources detected in the ASCA Large Sky Survey. Optical spectroscopic observations were done for 34 X-ray sources which were detected with the SIS in the 2-7 keV band above 3.5 sigma. The sources are identified with 30 AGNs, 2 clusters of galaxies, and 1 galactic star. Only 1 source is still unidentified. The flux limit of the sample corresponds to 1 x 10^{-13} erg s^{-1} cm^{-2} in the 2-10 keV band. Based on the sample, the paper discusses optical and X-ray spectral properties of the AGNs, contribution of the sources to the Cosmic X-ray Background, and redshift and luminosity distributions of the AGNs. An interesting result is that the redshift distribution of the AGNs suggests a deficiency of high-redshift (0.5 < z < 2) and luminous (Lx(2-10 keV) > 10^{44} erg s^{-1}) absorbed narrow-line AGNs (so called type 2 QSOs).
Cite
@article{arxiv.astro-ph/0001289,
title = {Optical Identification of the ASCA Large Sky Survey},
author = {M. Akiyama and K. Ohta and T. Yamada and N. Kashikawa and M. Yagi and W. Kawasaki and M. Sakano and T. Tsuru and Y. Ueda and T. Takahashi and I. Lehmann and G. Hasinger and W. Voges},
journal= {arXiv preprint arXiv:astro-ph/0001289},
year = {2009}
}
Comments
Accepted for publication in ApJ. 57 pages with 13 figures, 9 JPG plates, 5 additional PS tables. Original EPS plates (gzipped format ~1Mbyte/plate) and TeX tables are available from ftp://ftp.kusastro.kyoto-u.ac.jp/pub/akiyama/0001289/