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G. Hasinger (Max-Planck-Institut fuer extraterrestrische Physik), Chandra Deep Field South Team
Spectroscopic optical identifications of the X-ray sources discovered in the Mega-second exposure of the Chandra Deep Field South have been performed with the ESO Very Large Telescope on Paranal/Chile. Observations have been performed during 11 nights distributed between October 2000 and November 2001. Exposures using the multiobject spectrographs FORS1 and FORS2 on the telescopes UT1, UT3 and UT4 ranged up to 4 hours per mask.
More than 150 quality spectra could be secured so far and optical identifications in a subset area of the CDFS are complete to more than 60 faint X-ray sources contains ample numbers of heavily obcured active galactic nuclei predicted by the population synthesis models, in paticular a population of high luminosity obscured QSOs. Also normal X-ray emitting galaxies at moderate redshifts and faint groups/clusters of galaxies are among the sample.
The distribution of source classes and the redshift distribution will be presented. Necessary modifications to models for the cosmological evolution of the AGN X-ray luminosity function and to the population synthesis models for the X-ray background will be discussed.
The author(s) of this abstract have provided an email address for comments about the abstract: ghasinger@mpe.mpg.de