By John Kessler
According to new simulations, a huge number of rogue supermassive black holes could wander through the universe. There are 12 such giants at the edge of the Milky Way.
Astronomers believe that most galaxies form around supermassive black holes. Giant gravitational objects, millions and billions of times more massive than the Sun, act as anchors for long plumes of gas, dust, stars and planets that orbit around them. Closer to black holes, this material spirals faster and heats up, forming an accretion disk. It feeds the black hole and produces the very radiation that makes it visible.
Usually, the mass of these black holes “cements” them at the centers of galaxies, which slowly rotate in clusters. But sometimes a huge force – like a collision of two galaxies – can push the central supermassive black hole and force it to wander through the universe. Violation of the process of merging black holes also leads to the fact that one of them becomes “wandering”.
To assess how often this happens, astronomers have conducted a series of simulations that take into account all the known characteristics and “rules of behavior” of black holes. The goal is to track how their orbits have evolved over billions of years.
Simulations predicted that frequent galactic collisions in the early universe between the Big Bang event about 13.7 billion years ago and 2 billion years later generated enough space wanderers. Their number exceeds the number of supermassive black holes recorded in the center of galaxies. The study found that there are at least 12 such wandering objects on the outskirts of the Milky Way.