VHE Gamma-rays from Galactic X-ray Binary Systems
The detection of TeV gamma-rays from LS 5039 and the binary pulsar PSR B1259-63 by HESS, and from LS I +61 303 and the stellar-mass black hole Cygnus X-1 by MAGIC, provides a clear evidence of very efficient acceleration of particles to multi-TeV energies in X-ray binaries. These observations demonstrate the richness of non-thermal phenomena in compact galactic objects containing relativistic outflows or winds produced near black holes and neutron stars. I review here some of the main observational results on very high energy (VHE) gamma-ray emission from X-ray binaries, as well as some of the proposed scenarios to explain the production of VHE gamma-rays. I put special emphasis on the flare TeV emission, suggesting that the flaring activity might be a common phenomena in X-ray binaries.