Gamma ray observations of polars

Abstract

Experimental evidence is reported for the discovery of an entirely new class of gamma-ray binary objects involving a magnetic white dwarf rather than a neutron star degenerate primary. These sources may have photon energies extending into the PeV range. The gamma-ray light curves exhibit a striking morphological similarity with corresponding phase dependence of the circularly polarized light from the sources. If confirmed, these results will have important consequences for the physics underlying acceleration of high-energy particle beams in binary systems as well as for the contribution of unresolved point sources in the Galactic gamma-ray background