Investigation of the physics of wind interactions in colliding-wind massive binaries through XMS high resolution X-ray spectroscopy

Binary systems made of two massive stars offer the opportunity to investigate the physics of quite extreme stellar environments. The powerful stellar winds collide, producing so-called wind interaction regions, and the shocked gas is heated up to temperatures that can reach values as high as several tens of MK, leading to the production of copious amounts of thermal X-rays. The properties of the X-ray spectrum of such systems are intimately related to the orbitally modulated physical conditions in the wind interaction region. The study of the hydrodynamics of the colliding-wind phenomenon is a crucial issue in the sense that it constitutes the basement for the study of higher level physical processes at work in these systems, such as particle acceleration or even dust production. High-resolution X-ray spectroscopy with ATHENA/XMS is undoubtedly expected to be the most powerful tool to probe the physics of such environments over the next two decades, allowing a detailed confrontation to state-of-the-art theoretical models aiming at simulating the complex physics of colliding-wind massive binaries (CWBs).