ESA’s XMM-Newton X-ray Space Telescope has put out the latest edition of its catalogue of X-ray sources. Called 2XMMi-DR3,the catalogue contains x-ray sources captured in the background as primary targets were observed. The satellite turns to face around 600 targets a year with an average diameter close to that of the full Moon. This leaves a lot of space around the source on images retrieved by the ground crew that can then be scanned for smaller sources, averaging about seventy per primary source, providing close to 40,000 additional detections a year, 98% of them entirely new to science.
Among the serendipitous discoveries was a 500 solar mass black hole like source that bridged the gap between stellar mass black holes formed by exploding stars and supermassive black holes, whose origins are more controversial, but which possibly formed from the merger of intermediate mass black holes – such as 500 solar mass ones.
The catalogue is now around three times larger than the ROSAT cataloge with quarter of a million sources (likely to double in the next 5-6 years) and compliments small scale surveys done by telescopes such as Chandra and XMM-Newton in the past, which have looked at a smaller region of the sky with longer exposures.
More detail on the catalogue, including how to get at it, can be found here.