Collisions between two galaxies may explain why supermassive black holes form develop in them, according to a new research by an international team headed by Dr John Silverman of the University of Kashiwa, Japan. These supermassive black holes are usually found in the most massive galaxies, and that their size is proportional to the "bulge" in the center of the galaxy -- that is the mass of the stars in the middle.
The team used X-ray scans from NASA's Chandra observatory to identify galaxies with a growing super massive black hole -- the huge objects often release X-rays in their growth stages, and X-rays shoot straight through star-forming regions to give a clear picture of the number of the black holes.
The team's report, published in the Astrophysical journal, said that galaxies in close pairs -- as measured by the redshift survey from the European Southern Observatory's Very Large Telescope -- are twice as likely to be inhabited super massive black holes.
Interactions between galaxies are fairly rare, and the team estimated that only around 20 per cent of the mass of black holes can be accounted for by these collisions. So some X factor is causing the black holes to grow -- perhaps the final stages of galaxies coalescing into one, the researchers said.
The image below shows time evolution of the nuclear gas disk from its formation until the onset of central collapse.
Source: The Daily Galaxy - astrophysical journal