Astronomers have long studied supermassive black holes and smaller black holes that form when massive stars implode, but they have searched for intermediate-mass black holes for years.
Now, thanks to observations by the Hubble Space Telescope, astronomers have found their “missing link” to understand how black holes evolve. They were able to confirm the observation of an intermediate-mass black hole, known as an IMBH, inside a dense cluster of stars.
The study published this week in the Astrophysical Journal Letters.
Only a few other possible mid-range black holes have been found before. They’re difficult to detect because they’re smaller than the supermassive black holes that can be found at the heart of large galaxies. At the same time, they’re larger than black holes that form when stars collapse and die.
The nature of these mid-range black holes makes them harder to spot because they aren’t as active as supermassive black holes. They are also lacking the telltale gravitational pull on objects around them, which can create a detectable X-ray glow.
This particular black hole is more than 50,000 times the mass of our sun.
“Intermediate-mass black holes are very elusive objects, and so it is critical to carefully consider and rule out alternative explanations for each candidate. That is what Hubble has allowed us to do for our candidate,” said Dacheng Lin, principal investigator of the study and research assistant professor at the University of New Hampshire.
Hubble was used to follow up on observations previously made by NASA’s Chandra X-ray Observatory and the European Space Agency’s X-Ray Multi-Mirror Mission. Both were launched in 1999 and have been providing X-ray observations of space ever since.
They first detected X-ray flares in 2006 that might signify a black hole, but astronomers couldn’t tell based on data if the signal was within our galaxy or outside of it.