  General properties of accretion onto isolated stellar mass black holes in the
Galaxy are discussed. An analysis of plasma internal energy growth during the
infall is performed. Adiabatic heating of collisionless accretion flow due to
magnetic adiabatic invariant conservation is 25% more efficient than in the
standard non-magnetized gas case. It is shown that magnetic field line
reconnections in discrete current sheets lead to significant nonthermal
electron component formation, which leads to a formation of a hard (UV, X-ray,
up to gamma), highly variable spectral component in addition to the standard
synchrotron optical component first derived by Shvartsman generated by thermal
electrons in the magnetic field of the accretion flow. Properties of accretion
flow emission variability are discussed. Observation results of two single
black hole candidates - gravitational lens MACHO-1999-BLG-22 and radio-loud
x-ray source with featureless optical spectrum J1942+10 - in optical band with
high temporal resolution are presented and interpreted in the framework of the
proposed model.
