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Posted: Jul 23, 2013
A new record for cosmic X-ray sightings
(Nanowerk News) The release of a new catalogue from the XMM-Newton space telescope provides an unprecedented cosmic X-ray library for the exploration of the extreme Universe. The third XMM-Newton Serendipitous Source Catalogue (3XMM-DR4) contains more than half a million sources, all of which are provided to a better quality than ever before. Improved data processing means that source identification is more reliable, and fainter objects are detected.
This is a sky distribution of the density of objects in the 3XMM catalog, shown in Galactic coordinates. The inset shows a zoom of the small region indicated where the individual sources can be seen. (Credit: ESA/XMM-Newton/EPIC/M. Watson (University of Leicester))
The catalogue provides an exceptional dataset for generating large, well-defined samples of objects such as active galaxies (which dominate the detections in this catalogue), clusters of galaxies, interacting compact binaries, and active stellar coronae. This vast inventory is also home to some of the rarest and most extreme phenomena in the Universe, such as tidal disruption events - when a black hole swallows another star, producing prodigious outbursts of X-ray emission.
"The catalogue provides plenty of scope for new discoveries as well as in-depth studies of large samples," says Professor Mike Watson of the University of Leicester, who leads the XMM-Newton Survey Science Centre (SSC).
"XMM-Newton is pre-eminent amongst current X-ray missions in its ability to perform 'survey' science, with a chance to find previously undetected objects and then explore their properties."
The sources in the 3XMM catalogue are identified and isolated from serendipitous data recorded by XMM-Newton's EPIC X-ray cameras. In each of the 600-700 observations made each year, around 70 extra sources are captured in addition to the target object which usually only takes up a small fraction of the field of view. Covering observations between February 2000 and December 2012, the catalogue contains some 531 261 X-ray source detections relating to 372 728 unique X-ray sources.
"The third XMM-Newton Serendipitous Source Catalogue shows how much added value can be gained from the observations," notes Watson. "I'd like to pay tribute to the efforts of the whole team which were crucial to completing this major undertaking."
Natalie Webb of the Institut de Recherche en Astrophysique et Planétologie, Toulouse is taking over from Leicester's Simon Rosen as the SSC Manager for the next phase of the project. She comments: "Previous versions of the catalogue have yielded unexpected and exciting results, and with around 50 per cent more data now available, there should be plenty more to come. I look forward to the SSC continuing to play its leading role in this area."
Coinciding with the publication of the 3XMM catalogue, a new version of the XMM-Newton Science Archive (XSA) is released, providing convenient access to the catalogue. The most visible change in XSA is the new web-based interface, but behind the scenes many changes have been introduced to make it easier and quicker to find and use the data.
XMM-Newton Archive Scientist Nora Loiseau took detailed feedback from the XMM-Newton community to define the capabilities needed for the new system to allow scientists to carry out research using data from the archive. The new archive is significantly faster, mainly because it uses different algorithms for indexing and searching. Searches are typically more than twenty times faster than before, and the new archive also facilitates some complex searches which had not been possible on the old system.
The 3XMM-DR4 catalogue is the sixth publicly released XMM-Newton X-ray source catalogue produced by the XMM-Newton Survey Science Centre consortium on behalf of ESA.