X-ray monitoring of optical novae in M 31 from July 2004 to February 2005

摘要: Context. Optical novae have recently been identified as the major class of supersoft X-ray sources in M 31 based on ROSAT and early XMM-Newton and Chandra  observations. Aims. This paper reports a search for counterparts optical archival  HRC-I ACIS-I well XMM-Newton observations galaxy center region obtained from July 2004 to February 2005. Methods. We systematically determine brightness or upper limit all known with outbursts between November 2003 end coverage. In addition, we brightnesses four earlier outbursts. Results. For comparison data created catalogue our own nova programs reported literature. collected properties named consistently following CBAT scheme. detect eleven out 34 within year after outburst X-rays. While source phase, seven are still bright more than 1200, 1600, 1950, 2650, 3100, 3370 3380 d outburst. One is detected turn 50 d, another 200 Three unexpectedly showed short starting lasting only two three months. The emission several can be characterized hardness ratios and/or spectra by comparing HRC-I count rates limits. Conclusions. number at X-rays much higher previously estimated (>$30\%$). use light curves estimate burned masses White Dwarf ejecta.