Astronomers Find 400 Hidden Black Holes With NASA's Chandra Observatory

More than 400 previously undiscovered black holes that consume stars and dust in the centre of galaxies have been found by astronomers. It appears that many of the new black holes that were found by using NASA's Chandra X-ray Observatory were hidden under dust cocoons up until this point.

The supermassive black holes have millions or perhaps billions of times the mass of the Sun. Although it is believed that nearly all large galaxies contain massive black holes at their centres, only some of the black holes will be actively absorbing radiation and some will be hidden beneath dust and gas, the American space agency stated.

"Astronomers have already identified huge numbers of black holes, but many remain elusive," said Dong-Woo Kim of the Center for Astrophysics in a press release. He continued, "Our research has uncovered a missing population and helped us understand how they are behaving."

Scientists have known for about 40 years about galaxies that appear normally in optical light - with light from stars and gas but without the distinctive optical signatures of a quasar - but shine brightly in X-rays. These are known as "X-ray bright optically normal galaxies," or "XBONGs." To further investigate these mysterious entities, the team examined a catalogue of over three lakh bright X-ray objects captured by Chandra.

They then used optical images of the night sky from the Sloan Digital Sky Survey to search for X-ray bright but optically normal objects. The researchers discovered 820 XBONGs between 550 million and 7.8 billion light-years from Earth, the largest sample ever assembled, according to Mr Kim.

Co-author Alyssa Cassity, a graduate student at the University of British Columbia said in a press release, "It's not every day that you can say you discovered a black ho. So, it's very exciting to realize that we have discovered hundreds of them."