Two of the black holes are estimated to weight about 50 and 100 million solar masses each, while the third is a colossal 500 million times more massive than our Sun. The galaxies lie between 32 and 50 million light-years from Earth.
Astronomers suggest the supermassive black holes are the remains of fossil quasars.
Quasars, observed far out towards the edge of the universe, are huge superluminous objects which emit as much energy as a hundred super giant galaxies. Quasars are thought to represent an early stage of galaxy formation, and the supermassive black holes seen in the galaxies much closer to home may mark the sites where quasars once existed. The results are part of a census of 27 nearby galaxies which indicate that supermassive black holes are common within large galaxies. Furthermore, it seems that the mass of the black holes are proportional to the mass of the galaxies they lie in, but the reason for their abundance, and why they should be proportional to the mass of their host galaxy is not yet fully understood. One theory is that the black hole was once quite modest, but has 'grown' from the consumption of star materials over aeons of time.