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Issue A&A
Volume 373, Number 1, July I 2001
Page(s) 63 - 99
Section Extragalactic astronomy
DOI http://dx.doi.org/10.1051/0004-6361:20010495



A&A 373, 63-99 (2001)
DOI: 10.1051/0004-6361:20010495

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

R. Supper1, G. Hasinger1, 2, W. H. G. Lewin3, E. A. Magnier4, J. van Paradijs5, 6, W. Pietsch1, A. M. Read1 and J. Trümper1

1  Max-Planck-Institut für extraterrestrische Physik, Postfach 1603, 85740 Garching, Germany
2  Astrophysikalisches Institut, An der Sternwarte 16, 14482 Potsdam, Germany
3  CSR and Department of Physics, Massachusetts Institute of Technology, Room 37-627, Cambridge, MA 02139, USA
4  Canada-France-Hawaii Telescope, 65-1238 Mamalahoa Hwy, Kamuela, HI 96743, USA
5  Astronomical Institute "Anton Pannekoek" , University of Amsterdam, Kruislaan 403, 1098 SJ Amsterdam, The Netherlands
6  Physics Department, University of Alabama in Huntsville, Huntsville, AL 35899, USA

(Received 6 February 2001 / Accepted 2 April 2001 )

Abstract
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.(1997). 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 $7\times 10^{-15} {erg cm}^{-2} { s}^{-1}$ to $7.6\times 10^{-12} {erg cm}^{-2} {s}^{-1}$, 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 $4\times 10^{35} { erg s}^{-1}$ to $4\times 10^{38} { erg s}^{-1}$. The total (0.1 keV-2.0 keV) luminosity of M 31 is $(3.4\pm0.3)\times 10^{39} {erg s}^{-1}$, 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 $(2.0\pm0.5)\times 10^{38} { erg s}^{-1}$. An explanation in terms of hot gaseous emission leads to a maximum total gas mass of $(1.0\pm0.3)\times 10^6 M_{\odot}$.


Key words: galaxies: fundamental parameters -- galaxies: individual: M 31 -- galaxies: spiral -- X-rays: galaxies

Offprint request: R. Supper, ros@mpe.mpg.de

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© ESO 2001


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