Largest catalogue of X-ray detected astrophysical objects published

28 April 2015. A systematic analysis of all observations performed so far by the X-ray satellite XMM-Newton resulted in the worlds most comprehensive catalogue of X-ray detected celestial objects. It was compiled and published by a science consortium, the XMM-Newton Survey Science Centre, the AIP being one of its members. The catalogue, called 3XMM-DR5, lists 565 962 X-ray detections, ranging from nearby objects in our Solar System to supermassive black holes at the edge of the Universe. For each detection, a wealth of information is provided to help understand the nature of the object and as a result, many new and extreme astrophysical objects will be discovered.

Sources that are bright in X-ray light are amongst the most energetic in the Universe. The European Space Agency's highly sensitive XMM-Newton X-ray observatory detects 50-100 X-ray sources in a region of the sky that is the same size as the full moon, and there are around 600 such observations per year. Many of the detections turn out to be objects that have never previously been observed.

Axel Schwope, team lead at the Leibniz Institute for Astrophysics Potsdam (AIP), which is responsible for the source detection software, says: “50 years ago just a handful of X-ray sources were known and scientist entered unchartered territory. Now, with half a million sources, one can make on the one hand a census of the more common objects and on the other hand search for very rare exotic objects.” Iris Traulsen, project scientist at AIP, adds: “Our source detection software is an important tool for those searches. It was continuously improved over the last years, an effort that led to an ever enhanced precision of the detection process.”

The X-ray sources in the XMM-Newton serendipitous source catalogue are objects such as supermassive black holes guzzling the gas and dust that surrounds them in the centres of galaxies, exploding stars and dead stars that have collapsed to tight balls of exotic material that are as dense as the atomic nucleus and rotate up to 1000 times per second. However, new and exotic objects are expected to be found, based on results from previous smaller versions of the catalogue.

Indeed, during the methodical data validation phase, two new extreme binary systems, known as polars were discovered. These systems contain a star like our Sun and the remains of a star that has collapsed into a 'white dwarf'. The two objects orbit each other (much like the Earth and the Moon) and the white dwarf is so dense (1 million times the density of water!) that it strips the outer layers from its companion star through its huge gravitational field. This gas and dust gets caught in the white dwarf's extra-strong magnetic field (ten million times stronger than the Earth's magnetic field) causing it to heat up and radiate strongly in the X-ray domain. In the extreme case, it is possible that so much matter can fall onto the white dwarf that it would no longer be able to support its own weight, therefore such kind of objects are candidates progenitors for type Ia supernova explosions. These explosions allow astronomers to measure the distance to remote objects in the Universe.

Natalie Webb from the Institut de Recherche en Astrophysique et Planétologie (IRAP, Toulouse, France), who is responsible for the XMM-Newton Survey Science Centre that produces the catalogue, enthuses: “This is just the tip of the iceberg – there are many more new and exciting objects waiting to be discovered in the catalogue!”

In order for scientists to make the most of the catalogue, a scientific paper submitted to the European Journal Astronomy and Astrophysics, written by the XMM-Newton Survey Science Centre consortium, describing the catalogue and its products accompanies the release of this prestigious catalogue, along with a new version of the XMM-Newton Survey Science Centre webpages.

Caption: On the map of the sky each dot represents one observation with XMM-Newton. Each of it corresponds to the size of the full moon. The galactic centre and the galactic plane (centre of the map) and our neighbour galaxies, the Magellanic clouds (lower right) were targeted often. Some of the ‘exotic animals in the high-energy zoo’ are also depicted (artists impression).



IRAP press release

The XMM-Newton Survey Science Centre webpages and catalogue access:

The paper describing the catalogue: 'The XMM-Newton serendipitous survey VI. The third XMM-Newton serendipitous source catalogue', S. R. Rosen, N. A. Webb, M. G. Watson et al., A&A.


Science contact AIP: Dr. Axel Schwope,+49 331 7499-232,

Media contact AIP: Dr. Janine Fohlmeister, +49 331 7499-383,

Media contact XMM-Newton Survey Science Centre: Dr. Natalie Webb,

The key topics of the Leibniz Institute for Astrophysics Potsdam (AIP) are cosmic magnetic fields and extragalactic astrophysics. A considerable part of the institute's efforts aim at the development of research technology in the fields of spectroscopy, robotic telescopes, and e-science. The AIP is the successor of the Berlin Observatory founded in 1700 and of the Astrophysical Observatory of Potsdam founded in 1874. The latter was the world's first observatory to emphasize explicitly the research area of astrophysics. Since 1992 the AIP is a member of the Leibniz Association