Intermediate black holes could tell us how galaxies are formed, as well as how black holes go from teeny tiny to being supermassive. Intermediate black holes have been known about for some time; the same research team responsible for the current findings, led by the University Of Sydney's Dr Sean Farrell discovered the first of its kind that we knew about, called HLX-1 back in 2009.
Now by using the Hubble telescope and new modelling techniques, the team's been able to detect the presence of a very young massive cluster of stars around HLX-1 itself. HLX-1 is, in universal terms, a rather titchy little thing — although to earthy scale, still massive. A paper released by the Australian Media Science Centre quotes Dr Farrell
Astronomers have classified black holes into stellar mass black holes, which are up to tens of times the mass of our Sun, and supermassive black holes, which are millions to billions of times the mass of our Sun. HLX-1 lies in between at around 20 000 times the mass of our Sun.
Our latest finding is that we’ve detected evidence for a very young massive cluster of stars around the HLX-1 black hole. The fact that it’s a very young cluster of stars indicates that our Intermediate Mass Black Hole may have originated as the central black hole in a very low mass dwarf galaxy, that has been swallowed by the massive galaxy that it now resides in.
This has really important implications for how supermassive black holes form, and therefore how galaxies form and evolve. Before this finding, we had very strong evidence for the existence of Intermediate Mass Black Holes, but we weren't sure where they were formed. Now we may understand where they come from.
This conclusion opens up many other opportunities for us to begin targeted observations, mainly with NASA’s Chandra space telescope, in order to find more potential Intermediate Mass Black Holes. Intermediate Mass Black Holes are a crucial missing link between stellar mass and supermassive black holes, and may turn out to be the building blocks of the supermassive black holes found in the centres of galaxies. Our own Milky Way galaxy may be filled with them.'
[Astrophysical Journal] Image: a composite Hubble Space Telescope image of the galaxy ESO 2430–9 in which the intermediate mass black hole HLX–1 resides/NASA/STScI/Farrell et al. (2012)