  Most stellar remnants so far have been found in binary systems, where they
interact with matter from their companions. Isolated neutron stars and black
holes are difficult to find as they are dark, yet they are predicted to exist
in our Galaxy in vast numbers.
  We explored the OGLE-III database of 150 million objects observed in years
2001-2009 and found 59 microlensing events exhibiting a parallax effect due to
the Earth's motion around the Sun. Combining parallax and brightness
measurements from microlensing light curves with expected proper motions in the
Milky Way, we identified 13 microlensing events which are consistent with
having a white dwarf, neutron star or a black hole lens and we estimated their
masses and distances. The most massive of our black hole candidates has 9.3
MSun and is at a distance of 2.4 kpc. The distribution of masses of our
candidates indicates a continuum in mass distribution with no mass gap between
neutron stars and black holes. We also present predictions on how such events
will be observed by the astrometric Gaia mission.
