In the Milky Way there’s a single X-ray binary — a system consisting of a black hole capturing and heating material from an orbiting companion star — known as Cygnus X-1. But 30 million light-years away in the Whirlpool galaxy, M51, there are hundreds of X-ray points of light and a full 10 X-ray binaries. Amazing!
But why is this galaxy dotted with black holes?
As hypothesized by Universe Today, the Whirlpool galaxy is thought to have so many X-ray binaries because it’s in the process of colliding with a smaller companion galaxy. This interaction triggers waves of star formation, creating new stars at a rate seven times faster than the Milky Way and supernova deaths at a rate 10-100 times faster.
The more-massive stars simply race through their evolution in a few million years and collapse to form neutron stars or black holes quickly. WOW!