New Galactic High Mass X-ray Binaries Discovered with INTEGRAL

Abstract

I will review the main observational properties of the new Galactic High Mass X‐ray Binaries (HMXBs) discovered by the INTEGRAL satellite in the hard energy range 17–100 keV. About 70% of the newly discovered HMXBs host OB supergiant companions and show peculiar properties with respect to classical HMXBs detected with previous missions: some of them display huge local absorptions, in excess of 1023 cm−2 (the so‐called obscured sources), while others show fast transient X‐ray emission, leading to the definition of a new sub‐class of HMXBs, the so‐called Supergiant Fast X‐ray Transients (SFXTs). Their peculiar behavior is still poorly understood and represents a challenge to theory.