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

The eROSITA telescope, developed by the Max Planck Institute for Extraterrestrial Physics, released its second data release (DR2), the most comprehensive catalog of the X-ray universe ever made. DR2 includes more than 1.9 million point-like sources and about 64,000 extended sources, nearly doubling the number from the original release. The catalog combines data from three full-sky scans and includes multi-wavelength information to connect X-ray detections with their optical and infrared counterparts. The study found that about 88% of the identified sources are extragalactic, primarily from actively accreting supermassive black holes.

• "eROSITA's second data release catalog delivering most comprehensive high-energy census of the cosmos to date" (2026, September 11) retrieved 12 September 2026 from https://phys.org/news/2026-09-erosita-comprehensive-high-energy-census.html

The DR2 catalog is the result of almost a decade of collaboration between the eROSITA and Sloan Digital Sky Survey. It enables the study of supermassive black holes and their evolution over cosmic time. The release includes data from Spektr-RG's first 556 days of observations, stacked to capture more faint objects. The data allows researchers to build 3D maps of active black holes and track their evolution. The study found that the most luminous black holes at high redshift are like needles in a haystack, and DR2 helped find more needles than expected, suggesting that rapidly growing black holes were more abundant in the early universe than previously thought.

• Mara Salvato, eROSITA spokesperson and chair of the follow-up working group, emphasized that X-ray detection is only the first step, and linking sources to other wavelengths helps determine their nature and cosmic distance.
• William Roster, lead author of the corresponding study, noted that DR2 provides a unique foundation for discoveries ranging from rare objects to large-scale population studies.

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