Mapping the extreme universe: Leicester publishes record-breaking astronomical catalogue

Posted by mjs76 at Apr 30, 2010 12:45 PM |
The largest catalogue of cosmic X-ray sources ever assembled has been made available by a team based in the University of Leicester’s X-ray and Observational Astronomy Group.
Mapping the extreme universe: Leicester publishes record-breaking astronomical catalogue

image: NASA

The snappily named Second XMM-Newton Serendipitous Emitting Object Catalogue, 2XMMi-DR3, listing more than a quarter of a million X-ray emitting objects, has been compiled from data collected by the XMM-Newton space telescope.

The University of Leicester is a major player in this ESA mission, leading both the international XMM-Newton Science Survey Centre (SSC) and the 'EPIC' instrument team which designed and built two of the photon imaging X-ray cameras onboard. The SSC team carries out the scientific processing of the raw data from the spacecraft as well as leading the XMM catalogue project. Both XMM teams are based in our Department of Physics and Astronomy.

XMM stands for X-ray Multi Mirror: the telescope has a total of 174 shells in its three X-ray mirrors, making it the most sensitive X-ray telescope ever built. It was launched from French Guiana aboard an Ariane 5 rocket in December 1999 and since then has been following an eccentric, 48-hour orbit around the Earth.

Every year, XMM-Newton makes about 600 astronomical observations of specific targets for researchers around the world. But because of its wide field of view (30 arc minutes – roughly equivalent to a full Moon) each image also contain lots of other X-ray sources, dubbed ‘serendipitous data’. Each year of operations yields an extra 40,000 of these, 98% of them previously undocumented.

The first XMM catalogue of serendipitous X-ray sources was published in April 2003 followed by higher quality updates in July 2006, August 2007 and August 2008, but the DR3 version, released this week, dwarfs them all. Drawing data from 4,953 observations made between February 2000 and October 2009, the catalogue lists 353,191 detections which, allowing for duplication, works out at 262,902 unique X-ray emitting objects.

Among the serendipitous X-ray sources identified in the XMM-Newton catalogues are the first intermediate-mass black hole to be conclusively identified (by a team including Leicester scientist Dr Sean Farrell) and the most massive galaxy cluster ever located, which provides some of the best evidence to date for the existence of 'dark energy'.

Professor Mike Watson, who leads the XMM-Newton Science Survey Centre, believes that there is plenty more to be found: "As the catalogue gets bigger it has more and more potential for exploring the extreme universe. At the current rate we'll reach half a million catalogued X-ray objects in the next five or six years."