Black Hole Candidates
Generally, any binary star system in which there is a strong X-ray source and in
which one of the stars is not seen but is very massive is a good candidate for a
black hole.
However,
accretion onto a black hole will look similar in many respects to accretion onto a neutron star or
white dwarf (see the discussion in the left frame).
Thus a careful study is required to distinguish black hole accretion from that
onto neutron stars or white dwarfs.