高能天体物理研究组知识库

We describe an ongoing programme to search for X-ray sources with long-term, large amplitude X-ray variability. The method is to compare the X-ray sources from the XMM-Newton Serendipitous Survey with those from the previous ROSAT pointed observations and the ROSAT All-sky Survey. The work is largely motivated by the recent discovery of a new type of X-ray flares characterised by enormous amplitude flux variability and associated with normal galaxies [Komossa, S., Ludwig Biermann Award lecture: X-ray evidence for supermassive black holes at the centers of nearby, non-active galaxies. Rev. Mod. Astron. 15, 27, 2002]. Other objects of interest are black hole accretion systems, such as X-ray binaries and AGN, GRB afterglows, extremes of stellar flares, and other objects undergoing extremely violent physical processes. In this paper, we describe the programme and present some preliminary results. (c) 2005 COSPAR. Published by Elsevier Ltd. All rights reserved.