Posters
Gandhi P, Crawford CS, Fabian AC, Wilman RJ, Johnstone RM
We present results of an ongoing programme to study the nature of the sources which are likely to comprise the bulk of the hard X-ray background(XRB). The X-ray bright (S(2-10\ keV) $\sim$ 10^{-14}$~erg~s$^{-1}$cm$^{-2}$), hard sources have been selected from a large sample of guaranteed-time Chandra 10-20 ksec cluster fields to have optically-faint counterparts. The X-ray spectra indicate a new population of heavily obscured quasars. The hard X-ray colours imply that the host galaxy is expected to dominate at optical/near-infrared wavelengths. The photometric redshifts of $\approx$ 30 objects indicate a distribution of absorbed early-type galaxies with a median redshift z$_{median}$=1.35. At least 10% of the sources in our sample have extremely red colours (R-K>=5.3)
Last Modified 08 Feb 2001.
On the nature of the hard XRB sources (gzipped version)