What Emits Astrophysical X-rays?
Cosmic X-rays span 2 bands:
0.12 to 12 keV: Soft X-rays
with super-soft X-rays being between 0.12 and 2.0 keV.
12 to 120 keV: Hard X-rays
What emits these astrophysical x-rays? A variety of objects and
processes, including but not limited to black hole accretion
disks in active galactic nuclei; emission from supernova remnants;
mass accretion due to Roche-lobe overflow in binary star systems
that contain a white dwarf, neutron star, or black hole (called
X-ray binares); and even
simple main sequence stars. Whether we see them or not will depend upon how close
they are to us, how sensitive our instruments are, and what
intervening matter might be in the path of this light.