Isolated black holes ( IBHs ) are not usually considered to be important astrophysical sources , since , even in the case of a high accretion rate , an accretion disk rarely can be formed due to the small angular momentum of the in-falling matter .
Thus , such systems are not expected to feature thermal disk emission which makes the dominant contribution to the radiative output of binary systems harbouring a BH .
Moreover , due to their relatively modest accretion rates , these objects are not conventionally treated as feasible jet sources .
However , the large number of IBHs in the Galaxy , estimated to be \sim 10 ^ { 8 } , implies a very high density of 10 ^ { -4 } pc ^ { -3 } and an average distance between IBHs of \sim 10 pc .
Our study shows that the magnetic flux , accumulated on the horizon of an IBH because of accretion of interstellar matter , allows the Blandford-Znajeck mechanism to be activated .
Thus , electron-positron jets can be launched .
We have performed 2D numerical modelling which allowed the jet power to be estimated .
Their inferred properties make such jets a feasible electron accelerator which , in molecular clouds , allows electron energy to be boosted up to \sim 1 PeV .
For the conditions expected in molecular clouds the radiative cooling time should be comparable to the escape time .
Thus these sources can contribute both to the population of unidentified point-like sources and to the local cosmic ray ( CR ) electron spectrum .
The impact of the generated electron CRs depends on the diffusion rate inside molecular clouds ( MCs ) .
If the diffusion regime in a MC is similar to Galactic diffusion , the produced electrons should rapidly escape the cloud and contribute to the Galactic CR population at very high energies > 100 TeV .
However , due to the modest jet luminosity ( at the level of \sim 10 ^ { 35 } erg s ^ { -1 } ) and low filling factor of MC , these sources can not make a significant contribution to the spectrum of cosmic ray electrons at lower energies .
On the other hand , if the diffusion within MCs operates at a rate close to the Bohm limit , the CR electrons escaping from the source should be confined in the cloud , significantly contributing to the local density of CRs .
The IC emission of these locally-generated CRs may explain the variety of gamma ray spectra detected from nearby MCs .