Do molecular clouds contain accreting black holes?

Spherical accretion of interstellar matter could reveal the presence of isolated black holes. Though the physical conditions of the diffuse interstellar medium are not suitable for efficient accretion, it has been suggested that Molecular Clouds (MCs), with their higher densities, could offer the environment for spherically acereting black holes to produce detectable fluxes. Calculating the birth rate of black holes and following their evolution in the galactic potential, we estimate their total number; however a detectable luminosity can be obtained only for slowly moving sources which result to be ∼ 0.5 - 7 per MC within 1 kpc from the Sun, depending on the initial velocity dispersion. The arising flux in this case turns out to peak at optical-infrared wavelength and we suggest some features which could help the identification.