Supermassive Black Holes Grow Faster Than Thought

The rate of growth of two nearby black holes has been found to be greater than their host galaxies themselves. The new research could help scientists understand how galaxies and black holes evolve together.

Scientists compared the sizes of the black holes' bulges with the mass and dark matter of the black hole. Bulges are the cluster of densely packed stars that surround a black hole. Typically, a black hole will account for 0.2 percent of the bulge's mass.

However, the supermassive black holes in galaxies  NGC 4342 and NGC 4291 are 10 to 35 times bigger than they should be. The dark matter enveloping these black holes is also overweight.

"This gives us more evidence of a link between two of the most mysterious and darkest phenomena in astrophysics -- black holes and dark matter -- in these galaxies," said study leader Akos Bogdan of the Harvard-Smithsonian Center for Astrophysics (CfA) in Cambridge, Mass.

The data was collected using NASA's Chandra X-ray Observatory.

The large relative size of these black holes are most likely due to the to the black hole feeding on the mass of hot gas in the galaxy's center. As the black hole gets larger, it shoots out radiation, x-rays, and various matter which keep the gas from cooling and forming new stars.

It was previously thought that tidal stripping was the reason for a lack of stars compared to the black holes. Tidal stripping is when galaxies collide and the gravity from the other one "strips" away stars from the other. However, this would leave trails of dark matter, which gets stripped away easier than stars, and that is not what scientists have observed.