Results from the Serendipitous Extragalactic X-ray Source Identification (SEXSI) Program
F. A. Harrison(Caltech) D. J. Helfand (Columbia University) P. H. Mao (Caltech) D. Stern (JPL) J. Chakan (Caltech) S. G. Djorgovski (Caltech) E. Laird (Columbia University)
Abstract
The raison d'etre for the Chandra Observatory when it was proposed 25 years ago was to resolve the X-ray background. It is not clear whether this goal will literally be achieved by Chandra, but it is already apparent from the first moderately deep pointings that new contributing populations are being discovered. To date, extensive optical followup has been concentrated in a few of the deepest fields. It is now clear that the limited survey area covered by these deep exposures is insufficient to answer many interesting questions related to the evolution of high energy source populations.
The SEXSI survey is extending deep optical and infrared followup
of hard X-ray (2 - 10 keV) selected sources in a sky area increased
more than an order of magnitude compared to the Chandra deep
fields. We have accumulated over two dozen extragalacted Chandra
fields with X-ray exposures ranging from 50 - 200 ksec. These contain
more than 700 hard-band-selected sources in an area of deg2. We have completed deep imaging on most of these fields using
the Palomar 60
and 200
and the MDM 2.4 m
telescopes, and spectroscopy on more than 150 sources using Keck/LRIS.
In this paper we present results from the survey to-date, including
the optical properties, classification, and redshift distribution of
more than 100 extragalactic spanning a wide range of X-ray
luminosities.
CATEGORY: GALACTIC DIFFUSE EMISSION AND SURVEYS