Obscured High Mass X-Ray Binaries and Supergiant Fast X-ray Transients:   Infrared Observations of INTEGRAL Sources
  A new type of high-energy binary system has been revealed by the INTEGRAL satellite. These sources are being unveiled by means of multi-wavelength optical, near- and mid-infrared observations. Among these sources, two distinct classes are appearing: the first one is constituted of intrinsically obscured high-energy sources, of which IGR J16318-4848 seems to be the most extreme example. The second one is populated by the so-called supergiant fast X-ray transients, with IGR J17544-2619 being the archetype. We report here on multi-wavelength optical to mid-infrared observations of a sample constituted of 21 INTEGRAL sources. We show that in the case of the obscured sources our observations suggest the presence of absorbing material (dust and/or cold gas) enshrouding the whole binary system. We finally discuss the nature of these two different types of sources, in the context of high energy binary systems. 
Sylvain Chaty (AIME, Universit\'e Denis Diderot - Paris VII, Sap)