NASA has pointed NuStar, or the Nuclear Spectroscopic Telescope Array, towards Andromeda, observing 40 X-ray binary systems. Since many only know X-rays from doctor’s or dentist’s appointments, here’s NASA on the subject and below is a video explaining X-rays in the Cosmos. Check out the Hawking-style voice!
As you can see, X-ray binaries occur when the more massive of two suns in a binary system explodes, forming either a neutron star, black hole, or white dwarf. The gravity of those can be immense enough that they can accumulate part of the secondary star’s material, thus creating temperatures of over a billion and a half degrees Fahrenheit (1x 10^9 K)!! This explosion then spreads massive amounts of X-rays or Gamma Rays across the universe. Andromeda is the only other system like our own close enough for us to study these binaries. You can read the rest of the story from NASA here.