Astronomers discover more than 800 new supermassive black holes

Using archival data from both the orbiting Chandra X-Ray telescope and the ground-based Sloan Digital Sky Survey telescope (SDSS), astronomers have discovered more than 800 new supermassive black holes hidden in the center of galaxies.

By systematically combing through the deep Chandra Source Catalog and comparing to SDSS optical data, the researchers identified 817 XBONG candidates, more than ten times the number known before Chandra was in operation. Chandra’s sharp images, matching the quality of those from SDSS, and the large amount of data in the Chandra Source Catalog made it possible to detect this many XBONG candidates. Further study revealed that about half of these XBONGs represent a population of previously hidden black holes.

The key to this discovery is the use of telescopes observing in different wavelengths, X-rays with Chandra and optical with SDSS. Combined the data showed evidence of the hidden supermassive black holes.