New Galactic High Mass X-ray Binaries discovered with INTEGRAL

TL;DR

This paper reviews the properties of newly discovered Galactic High Mass X-ray Binaries by INTEGRAL, highlighting their unique features such as high absorption and transient behavior, which challenge existing theoretical models.

Contribution

It provides a comprehensive overview of the observational characteristics of new HMXBs discovered by INTEGRAL, emphasizing their peculiar properties and classification.

Findings

70% host OB supergiant companions

Presence of highly absorbed and transient sources

Introduction of Supergiant Fast X-ray Transients as a new subclass

Abstract

I will review the main observational properties of the new Galactic High Mass X-ray Binaries 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 1E23 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. Their peculiar behavior is still poorly understood and represents a challenge to theory.