Describe the similarities and differences between radio pulsars and X-ray pulsars. Both radio pulsars and X-ray pulsars must be rotating, magnetic neutron stars. X-ray pulsars must therefore be in binary systems to have a supply of mass from the companion star. Radio pulsars are usually single and if they are in a binary, they cannot be accreting. Describe the observational evidence that astronomers have discovered black holes orbiting norma l stars in binary systems.
Astronomers study black holes by investigating X-rays coming from binary systems.
A very compact object, either a neutron star or a black hole, is required to produce the large gravity to heat matter falling inward. In practice, the X-rays come fromthe innermost, hottest regions of accretion disks where the matter is moving most rapidly. To differentiate neutron stars from blcak holes, astronomers use Keplar's laws to determine the mass of the compact object.