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Table 1
A selection of important X-ray surveys of M 31.
| Paper | S+ | #ofSrc* | L X † | Field | Comments |
| erg cm-2 s-1 | |||||
|
|
|||||
| Trinchieri & Fabbiano (1991, TF91) | E | 108 | 6.4 × 1036–1.3 × 1038 | entire set of Einstein | 16 sources showed variability |
| (0.2–4 keV) | imaging observations | ||||
| Primini et al. (1993, PFJ93) | R (HRI) | 86 |  1.8 × 1036 |
bulge region | 18 sources variable; ~3 transients |
| (0.2–4 keV) | |||||
| Supper et al. (1997, 2001) | R (PSPC) | 560 | 5 × 1035–5 × 1038 | whole galaxy | two deep surveys |
| (SPH97, SHL2001) | (0.1–2.4 keV) | 491 sources not detected with Einstein | |||
| 11 sources variable, 7 transients compared to Einstein | |||||
| 34 sources variable, 8 transients between ROSAT surveys | |||||
| Osborne et al. (2001) | X | 116 | 6 × 1035 |
centre | examined the ~60 brightest sources for variability |
| (0.3–12 keV) | |||||
| Kong et al. (2002b) | C (ACIS-I) | 204 | 2 × 1035 |
central ~17′ × 17′ | observations between 1999 and 2001 |
| (0.3–7 keV) | ~50% of the sources are variable, 13 transients | ||||
| Kaaret (2002) | C (HRC) | 142 | 2 × 1035–2 × 1038 | centre | one 47 ks observation; 46 ± 26% of the sources |
| (0.1–10 keV) | with LX > 5 × 1036 erg s-1 are variable | ||||
| Di Stefano et al. (2002) | C (ACIS-I/S) | 28 | 5 × 1035–3 × 1038 | 3 disc fields | bright X-ray binaries |
| (0.3–7 keV) | |||||
| Di Stefano et al. (2004) | C (ACIS-S S3) | 33 | 3 disc fields + centre | supersoft sources and quasisoft sources | |
| Williams et al. (2004) | C (HRC) | 166 | 1.4 × 1036–5 × 1038 | major axis + centre | 25% showed significant variability |
| (0.1–10 keV) | |||||
| Trudolyubov & Priedhorsky (2004) | C, X | 43 | ~1035– ~1039 | major axis + centre | globular cluster study |
| (0.3–10 keV) | |||||
| Pietsch et al. (2005b, PFH2005) | X | 856 | 4.4 × 1034–2.8 × 1038 | major axis + centre | source catalogue |
| (0.2–4.5 keV) | |||||
| Pietsch et al. (2005a, PFF2005) | C, R, X | 21 | ~1035– ~1038 | centre | correlations with optical novae |
| (0.2–1 keV) | |||||
| Orio (2006) | C, X | 42 | 6 × 1035– ~1039 | major axis + centre | supersoft sources and quasisoft sources |
| (0.2–2 keV) | |||||
| (0.3–10 keV) | |||||
| Pietsch et al. (2007, PHS2007) | C, X | 46 | ~1035– ~1038 | centre | correlations with optical novae |
| (0.2–1 keV) | |||||
| Voss & Gilfanov (2007) | C | 263 | 5 × 1033–1.5 × 1038 | bulge region | low mass X-ray binary study |
| (0.5–8 keV) | |||||
| Stiele et al. (2008, SPH2008) | X | 39 | 7 × 1034–6 × 1037 | centre | re-analysis of archival and new 2004 observations |
| 300 | 4.4 × 1034–2.8 × 1038 | time variability analysis; 149 sources with a significance | |||
| (0.2–4.5 keV) | for variability >3; 6 new X-ray binary candidates, | ||||
| 3 supernova remnant classifications were rejected | |||||
| Shaw Greening et al. (2009, SBK2009) | X | 335 | ~1034– ~1039 | 5 fields along | background subtracted spectra and lightcurves for |
| (0.3–10 keV) | major axis | each source; 18 HMXB candidates, selected from their | |||
| power law photon index | |||||
| Stiele et al. (2010) | X | 40 | whole galaxy | supersoft sources; comparing ROSAT, Chandra and | |
| XMM-Newton catalogues | |||||
Notes.
(+)
X-ray satellite(s) on which the study is based: E for Einstein, R for ROSAT, C for Chandra, and X for XMM-Newton (EPIC).
(†)
observed luminosity range in the indicated energy band, assuming a distance of 780 kpc to M 31.
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