Abstract

Contributed Talk - Splinter GWAstronomy

Thursday, 18 September 2025, 14:50

On the X-ray Emission of Massive Binary Stars

Martin Quast, Norbert Langer
Otto-von-Guericke Universität Magdeburg, Argelander-Institut für Astronomie Bonn

Gravitational wave detections have opened new avenues for studying massive binary systems, the progenitors of many stellar gravitational wave sources. However, in many such systems, only the brighter star is detectable via optical spectroscopy, while the companion remains unseen. Depending on its nature and system parameters, the companion may still produce X-ray emission. We present a method combining order-of-magnitude estimates of X-ray luminosity with optical measurements of the primary to constrain the properties of undetected companions in massive single-lined binaries. The results suggest that many more O-type stars may host X-ray quiet black hole companions than currently detected, as high wind velocities suppress accretion-driven X-ray emission.