Dark Matter Is Essential for Supermassive Black Holes

Don't ask me when the end of the world will come, I can't tell you, but one thing is for certain: a black hole could possibly trigger one. Especially taking into consideration the fact that about 30 percent of the total black holes population in the universe is thought to wander alone through space. Add the fact that they are mostly invisible to the electromagnetic spectrum while not feeding, and you have a possible recipe for disaster. No reason to fear though, we are not gonna be hit by one any time soon!

Monstrous objects with masses equal to that of a small galaxy, 18 billion times that of the Sun, may form in the most unexpected places. Supermassive black holes can be mostly found in the central cores of large galaxies. Nevertheless, observations made with the Spitzer Space Telescope reveal the fact that this is not always the case.

Galaxies represent large accumulations of stars. Our Milky Way alone packs about 200 billions of such objects; in the universe, there are possibly a few hundred billions of other galaxies. Most of these galaxies are spiral galaxies such as our own. Spiral galaxies are shaped in the form of a disks of material, with arms spiraling in a configuration resembling to a whirlpool. The density of the material is greater towards the center of the disk, and, when viewed from the plan of the disk, they appear to have galactic bulges.

Until recently, astronomers believed that supermassive black holes can only form in these galactic bulges, but it now seems that even thin galaxies that do not present such features might be able to create supermassive black holes. Thus, it was suggested that the size of the galactic core of a galaxy cannot be the only determining factor in the formation of a supermassive black hole at its core. It is now though that the growth of such monsters in thin galaxies may be determined by the presence of large clouds of dark matter.

The first evidence about the existence of such black holes in relatively thin galactic disks came in 2003, but it could not be explained how they came to grow to such massive sizes. Only recently it has been suggested that there might be a connection between the existence of the dark matter and supermassive black holes in minimal bulges of galactic disks.

The Spitzer Infrared Space telescope was able to penetrate the dusty central regions of galaxies with minimal bulges, to reveal more than six such massive black holes at their centers. Dark matter is believed to be a key element in the galaxy formation process and the evolution of the universe. Measurements currently suggest that it may account for more than two thirds of the mass of the entire universe, thus it could also be an important factor in the black holes evolution.