The deepest ROSAT surveys have shown, that, in the energy range 0.5-2.0 keV, QSO's can account for similar to 30 per cent of the Diffuse X-ray Background (DXRB), and Narrow Emission Line Galaxies (NELG) and clusters of galaxies for about 10 per cent each. But, by assuming characteristic spectral behaviour, known from bright archetypes of these classes, the faint ROSAT sources will, due to the hardness of the DXRB spectrum, only give an insignificant contribution at say 10 keV. By exploiting the excellent capability of the SODART telescopes to obtain broad band X-ray spectroscopy at energies > 2 keV, we propose to perform a spectroscopic survey with SODART and push these telescopes to the limit at the high energies. By selecting the four ESO Imaging Survey fields EIS teach 6 deg(2)) we will take full advantage of the large, systematic effort ESO is putting into the optical survey of these fields. This spectroscopic X-ray survey will provide a large, statistically complete, sample of sources detected at high energies, more than an order of magnitude fainter than obtained by previous missions. The study of these sources will significantly improve our understanding not only of the origin of DXRB, but also provide new insight into the evolution of galaxies, clusters of galaxies and AGN's.
|Publication status||Published - 1998|