The origin of the puzzling hard X-ray emission of $\gamma$ Cassiopeiae

Christian Motch, Raimundo Lopes de Oliveira, Myron A. Smith

Massive B and Be stars produce X-rays from shocks in high velocity winds with temperatures of a few million degrees and maximum X-ray luminosities of $\approx$ 10${}^{31}$ erg/s. Sur…