eROSITA has published a catalog of nearly 2 million X-ray sources
The German X-ray telescope eROSITA has released its second large data set, DR2, which includes a catalog of nearly 2 million cosmic X-ray sources. The list includes supermassive black holes, galaxy clusters, stars, and other high-energy objects. According to Space.com, this release has nearly doubled the number of X-ray sources known to astronomers.
The catalog combines the results of the first three all-sky surveys that eROSITA conducted over 556 days. This made it possible to detect fainter X-ray sources that had not been recorded in previous observations. More than 1.9 million objects in DR2 are point sources: most of them are active supermassive black holes at the centers of distant galaxies or stars in the Milky Way.
Approximately 64,000 additional sources were identified as extended. These include massive galaxy clusters, neighboring galaxies, and the remnants of supernova explosions. Galaxy clusters allow scientists to study the largest structures in the universe, including the influence of dark matter and dark energy on its evolution.
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X-ray radiation originates in some of the most energetic environments in space. Matter spiraling toward a black hole can heat up to millions of degrees before crossing the event horizon. Neutron stars, supernova remnants, and large reservoirs of hot gas in galaxy clusters also emit bright radiation in this range.
For many X-ray sources in the release, corresponding objects in the optical and infrared ranges are also listed. This helps determine the nature of the objects and their distance. Among the sources with identified counterparts, about 88% are distant galaxies hosting active supermassive black holes. eROSITA’s scientific observations ended in early 2022, but the data collected is sufficient for future public releases; DR3 is scheduled for 2028.
