Astronomers using the Hubble Space Telescope have found the best evidence so far for an elusive type of black hole known as an “intermediate-mass” black hole. The existence of the elusive kind of black hole was discovered after it tore apart a star that passed too close. Scientists say that the intermediate-mass black hole is about 50,000 times the mass of our Sun.
While that is certainly very massive, it’s significantly less than the mass of a supermassive black hole that is millions or billions of solar masses. Supermassive black holes typically live in the core of large galaxies. An intermediate-mass black hole has been searched out for a long time by scientists and is considered a “missing link” in black hole evolution.
Scientists consider the new Hubble discovery the most persuasive evidence yet for mid-size black holes in the universe. Scientists on the project use the Hubble space telescope to follow up on leads offered by the NASA Chandra X-ray Observatory and ESA X-ray Multi-Mirror Mission. In 2006, observatories detected a powerful flare of X-rays but were unable to determine if the flare originated from inside or outside our galaxy.
Researchers at the time attributed the X-ray flare to a star being torn apart after coming too close to a gravitationally powerful object, like a black hole. The surprise for the team was that the X-ray source, 3XMM J215022.4−055108, wasn’t in a galactic center where massive black holes typically reside. The location raised hope that they may have discovered an intermediate-mass black hole.
Hubble was later pointed at the source to resolve the precise location, ultimately finding that the source was not in our galaxy. Instead, it was in a distant, dense star cluster on the outskirts of another galaxy. Scientists say that was precisely the sort of location they expected to find an intermediate-mass black hole. Additional research is being conducted with the team hoping to learn if a supermassive black hole might be able to grow from an intermediate-mass black hole, among other solving other mysteries.