The second ROSAT PSPC survey of M 31 and the complete ROSAT PSPC source list

This paper reports the results of the analysis of the second ROSAT PSPC survey of M 31 performed in summer 1992. We compare our results with those of the first survey, already published in Supper et al. (\cite{Sup97}). Within the ~ 10.7 deg² field of view, 396 individual X-ray sources are detected in the second survey data, of which 164 are new detections. When combined with the first survey, this result in a total of 560 X-ray sources in the field of M 31. Their (0.1 keV-2.0 keV) fluxes range from 7x 10^-15 erg cm^-2 s^-1 to 7.6x 10^-12 erg cm^-2 s^-1, and of these 560 sources, 55 are tentatively identified with foreground stars, 33 with globular clusters, 16 with supernova remnants, and 10 with radio sources and galaxies (including M 32). A comparison with the results of the Einstein M 31 survey reveals 491 newly detected sources, 11 long term variable sources, and 7 possible transient sources. Comparing the two ROSAT surveys, we come up with 34 long term variable sources and 8 transient candidates. For the M 31 sources, the observed luminosities range from 4x 10³⁵ erg s^-1 to 4x 10³⁸ erg s^-1. The total (0.1 keV-2.0 keV) luminosity of M 31 is (3.4+/-0.3)x 10³⁹ erg s^-1, distributed approximately equally between the bulge and disk. Within the bulge region, the luminosity of a possible diffuse component combined with faint sources below the detection threshold is (2.0+/-0.5)x 10³⁸ erg s^-1. An explanation in terms of hot gaseous emission leads to a maximum total gas mass of (1.0+/-0.3)x 10⁶ M_sun. Tables 5, 6, 7 are also available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/373/63