Highly obscured IGR sources - The nature of the companion star
The INTEGRAL hard X-ray /soft gamma-ray observatory has revealed a
newly-discovered population of highly obscured X-ray binary systems.
To better understand this emerging population, Sylvain Chaty and
collaborators have selected a sample of INTEGRAL (IGR) sources
for which an accurate localisation was available. The aim of the
study was to identify the stellar counterpart and to reveal the
nature of the companion star and of the binary system.
A multi-wavelength optical to NIR study using the European Southern
Observatory (ESO) was performed in order to perform accurate astrometry
(shown in this Figure), photometry and spectroscopy of various candidate
counterparts. These multi-wavelength observations have shown that many
of these sources are high-mass X-ray binaries hosting neutron stars
orbiting around luminous and evolved supergiant companion stars.
INTEGRAL is therefore revealing a dominant class of obscured and
short-lived high-energy binary systems that stellar population models
should take into account for realistic estimates of high-energy binary
systems in our Galaxy.
Reference:
Chaty, Rahoui, Foellmi, Tomsick, Rodriguez, Walter,
A&A in press, 2008, vol 484, issue 3, first week of June.
