Recent discoveries of supersoft X-ray sources in M 31

✍ Scribed by M. Henze; W. Pietsch; F. Haberl; G. Sala; M. Hernanz; D. Hatzidimitriou; A. Rau; D.H. Hartmann; J. Greiner; M. Orio; H. Stiele; M.J. Freyberg

• Publisher: John Wiley and Sons
• Year: 2010
• Tongue: English
• Weight: 102 KB
• Volume: 331
• Category: Article
• ISSN: 0004-6337
• DOI: 10.1002/asna.200911325

✦ Synopsis

Abstract

Classical novae (CNe) have recently been reported to represent the major class of supersoft X‐ray sources (SSSs) in the central area of our neighbouring galaxy M 31. This paper presents a review of results from recent X‐ray observations of M 31 with XMM‐Newton and Chandra. We carried out a dedicated optical and X‐ray monitoring program of CNe and SSSs in the central area ofM 31. We discovered the first SSSs in M 31 globular clusters (GCs) and their connection to the very first discovered CN in a M 31 GC. This result may have an impact on the CN rate in GCs. Furthermore, in our optical and X‐ray monitoring data we discovered the CN M3 1N 2007‐11a, which shows a very short SSS phase of 29–52 days. Short SSS states (durations ≤ 100 days) of CNe indicate massive white dwarfs (WDs) that are candidate progenitors of supernovae type Ia. In the case of M31N 2007‐11a, the optical and X‐ray light curves suggest a binary containing a WD with M~WD~ > 1.0 M~⊙~. Finally, we present the discovery of the SSS counterpart of the CN M31N 2006‐04a. The X‐ray light curve of M31N 2006‐04a shows short‐time variability, which might indicate an orbital period of about 2 hours (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)