6 Conclusions

We performed an X-ray survey of a 8.95 deg² field in the direction of the Small Magellanic Cloud. We detect 248 point-like and moderately extended sources. Using criteria established here, six sources were classified as supersoft sources, 51 as hard X-ray binary candidates, 19 as supernova remnants, 19 as candidate foreground stars and 53 as candidate background AGNs. These are 60% of all catalog entries. The number of hard X-ray binaries agrees with the numbers predicted from population synthesis calculations for luminosities in excess of $10^{34}\ {\rm erg}\ {\rm s}^{-1}$. Assuming the standard $\log(N)-\log(S)$ of the soft extragalactic X-ray background we estimate that in our field are 10 background AGNs with fluxes in excess of $10^{-13}\ \rm erg\ {\rm cm}^{-2}\ {\rm s}^{-1}$ and 519 background AGNs with fluxes in excess of $10^{-14}\ {\rm erg}\ {\rm cm}^{-2}\ {\rm s}^{-1}$. We propose three new SNR candidates.

Acknowledgements

This research was supported in part by the Netherlands Organization for Scientific Research (NWO) through Spinoza Grant 08-0 to E.P.J. van den Heuvel. P.K. thanks E.P.J. van den Heuvel for stimulating discussions and X. Li for reading the manuscript. S. Stanimirovic is thanked for providing the HI image of the SMC. Part of the work has been performed during the stay of P.K. at the Max-Planck-Institut für extraterrestrische Physik in Garching. The ROSAT project is supported by the Max-Planck-Gesellschaft and the Bundesministerium für Forschung und Technologie (BMFT). This research made use of the Simbad data base operated at CDS, Strasbourg, France. We thank the referee for useful comments and suggestions to improve this work.