The strange case of HESS J0632+057 and the γ-ray High Mass X-ray Binaries

In the last decade Cherenkov telescopes on the ground and space-based γ-ray instruments have identified a new class of high mass X-ray binaries (HMXB), whose emission is dominated by γ rays. To date only five of these systems are known. All of them are detected by Cherenkov telescopes in the TeV energy range, while at GeV energies there is still one (HESS J0632+057) that has no reported detection with the Fermi-LAT. A deep search for γ-ray emission of HESS J0632+057 has been performed using more than 3.5 years of Fermi-LAT data. We discuss the results of this search and compare it to other γ-ray binary systems.