eROSITA's second data release catalog delivering most comprehensive high-energy census of the cosmos to date

The eROSITA telescope, aboard the Russian-German Spektr-RG space observatory, was built by the Max Planck Institute for Extraterrestrial Physics to observe X-rays from space. After launching in 2019, it has captured deep, detailed images across vast areas of the sky. The German eROSITA Consortium recently released its second data set (DR2), the most extensive catalog of high-energy sources in the universe to date.

DR2 incorporates data from three complete sky surveys and lists over 1.9 million point-like sources, mostly stars and actively accreting black holes, as well as about 64,000 extended sources, such as galaxy clusters and supernova remnants - almost double the amount from the initial release. These observations were gathered over the telescope's first 556 days of operation, conducted in six-month intervals.

Mara Salvato, spokesperson for eROSITA, explained that while X-ray detection is just the start, linking these sources to counterparts in other wavelengths allows researchers to determine the nature of these objects, their cosmic distances, and create high-quality samples on an unprecedented scale. The majority of the sources, 88%, are believed to be extragalactic, primarily supermassive black holes at the centers of galaxies beyond our own.

This release aligns with the 20th update of the Sloan Digital Sky Survey (SDSS DR20), which adds substantial optical spectroscopy from eROSITA-DE's surveys. This data combination marks a significant milestone, marking the culmination of a decade-long collaboration between the two surveys. With nearly 2 million sources cataloged in DR2, it provides astronomers with a unique and unprecedented foundation for studying a wide range of phenomena, from rare objects to large-scale population studies.