Astronomers using NASA's Chandra X-ray Observatory have discovered an intriguing cosmic object that may help provide answers to some long-standing questions about how black holes evolve and influence their surroundings.
The object, called NGC2276-3c, is located in an arm of the spiral galaxy NGC 2276-3c which is about 100 million light years from the Earth.
NGC2276-3c appears to be what astronomers call an "intermediate-mass black hole" (IMBH).
"Astronomers have been looking very hard for these medium-sized black holes. There have been hints that they exist, but the IMBHs have been acting like a long-lost relative that is not interested in being found," said study co-author Tim Roberts from the University of Durham in Britain.
Like paleontology, "we often have to 'dig' up our discoveries in galaxies that are millions of light years away", added Mar Mezcua from the Harvard-Smithsonian Centre for Astrophysics who led the study.
For many years, scientists have found conclusive evidence for smaller black holes that contain about five to 30 times the mass of the sun.
There is also a lot of information about so-called supermassive holes that reside at the centre of galaxies and weigh million or even billion times the Sun's mass.
As their name suggests, IMBHs represent a class of black holes that fall in between these two well-established groups, with masses in the range of a few hundred to a few hundred thousand solar masses.
One reason that IMBHs are important is that they could be the seeds from which supermassive black holes formed in the early universe.
"We found that NGC2276-3c has traits similar to both stellar-mass black holes and supermassive black holes," said co-author Andrei Lobanov of the Max Planck Institute for Radio Astronomy in Bonn, Germany.
"In other words, this object helps tie the whole black hole family together," the authors wrote.
In addition to its mass, another remarkable property of NGC2276-3c is that it has produced a powerful radio jet that extends up to 2,000 light years.
Further studies of the NGC2276-3c jet could provide insight into the potentially large effects that supermassive black hole seeds in the early universe have had on their surroundings.
The results are forthcoming in separate papers in the Monthly Notices of the Royal Astronomical Society.
