{
  "id": 6665263,
  "title": "eROSITA's Second Data Release Catalog Delivering the Most Comprehensive High-Energy Census of the Cosmos to Date",
  "url": "https://urgent.news/2026/09/10/erositas-second-data-release-catalog-delivering-the-most",
  "topic": "science",
  "section": "Science",
  "published": "2026-09-10T23:38:21.000Z",
  "source": {
    "name": "Universe Today",
    "slug": "universe-today",
    "url": "https://www.universetoday.com/articles/erositas-second-data-release-catalog-delivering-the-most-comprehensive-high-energy-census-of-the-cos"
  },
  "original_language": "en",
  "account": "The eROSITA telescope, aboard the Russian-German Spektr-RG space observatory, was built to study the soft X-ray sky. After its launch in 2019, it has produced deep, detailed images of large areas of the sky to map the high-energy Universe.\n\nIn the summer of this year, the German eROSITA Consortium released its second data catalog (DR2), the most comprehensive X-ray Universe catalog ever. By combining data from three full-sky scans, the DR2 lists over 1.9 million point-like sources (mainly stars and actively accreting black holes) and approximately 64,000 extended sources such as galaxy clusters and supernova remnants - nearly double the sources from the initial release.\n\nThis catalog includes data from multiple sky passes taken by the observatory every six months, which progressively improve depth and sensitivity. Dr. Mara Salvato, eROSITA spokesperson and chair of the follow-up working group, noted that X-ray detection is just the beginning. By linking X-ray sources to counterparts in other wavelengths, scientists can determine what these objects are, their cosmic distances, and create large, well-defined samples.\n\nThe DR2 comprises data from Spektr-RG's first 556 days of observations, which were stacked to detect fainter sources. The catalog also incorporates multi-wavelength information that matches detections with their most likely optical and infrared counterparts. The team found that around 88% of the identified sources are extragalactic, primarily featuring actively accreting supermassive black holes (SMBHs) at the centers of distant galaxies.\n\nThis release aligns with the twentieth version of the Sloan Digital Sky Survey (SDSS DR20), which includes significant optical spectroscopy from eROSITA-DE's surveys. These two datasets, representing almost a decade of scientific collaboration between the surveys, enable one of the largest and most detailed studies of SMBHs to date. This allows researchers to build 3D maps of active black holes and study their evolution over cosmic time.\n\nLead author Dr. William Roster explained that the most luminous black holes at high redshift are like needles in a haystack. Thanks to the DR2 catalog, they found more needles than expected, suggesting that rapidly growing black holes were more common in the early Universe than previously thought. Dr. Andrea Merloni, Principal Investigator of eROSITA, emphasized that the DR2 provides a unique foundation for discoveries spanning rare objects to large-scale population studies, now accessible to the global astronomical community with nearly 2 million sources.",
  "summary": "The eROSITA Consortium has issued the survey's second data release (DR2), nearly doubling the previously known eROSITA X-ray sources to two million.",
  "key_points": [
    "eROSITA telescope's second data catalog (DR2) released",
    "DR2 lists over 1.9 million point-like sources, 64,000 extended sources",
    "Catalog includes multi-wavelength information, aiding source identification"
  ],
  "editors_take": null,
  "illustration": null,
  "coverage": {
    "outlets": 1,
    "also_reported_by": []
  },
  "ai_generated": true,
  "disclaimer": "Summaries, key points and the editor’s take are written by software from other outlets’ reporting and may contain errors — always check the linked original."
}