  Current stellar evolution models predict that during the core collapse of
massive stars, a considerable amount of the stellar material will fall back
onto the compact, collapsed remnants (neutron stars or black holes), usually in
the form of an accretion disk. This triggers rapid mass accretion onto, e.g.,
the black hole, and produces energetic explosions known as Gamma-ray bursts.
However it is very difficult to prove the existence of an accretion disk around
newborn black holes observationally. Here we demonstrate that some of the
ultraluminous X-ray sources in nearby galaxies, which are associated with
supernova remnants, may be black holes accreting from their fallback disks,
i.e., they have evolved from collapsars. Since it is almost certain that there
is an accretion disk around these black holes, this would for the first time
lend the observational support to the collapsar model.
