New X-ray detections of known Wolf-Rayet stars

Abstract

Using XMM-Newton, we undertook a dedicated project to search for X-ray bright wind-wind collisions in 18 WR+OB systems. We complemented these observations with Swift and Chandra datasets, allowing for the study of two additional systems. We also improved the ephemerides, for these systems displaying photometric changes, using TESS, Kepler, and ASAS-SN data. Five systems displayed a very faint X-ray emission ($\log [L_{\mathrm{X}}/L_{\mathrm{BOL}}]<-8$) and three a faint one ($\log [L_{\mathrm{X}}/L_{\mathrm{BOL}}]\sim -7$), incompatible with typical colliding wind emission: not all WR binaries are thus X-ray bright. In a few other systems, X-rays from the O-star companion cannot be excluded as being the true source of X-rays (or a large contributor). In two additional cases, the emission appears faint but the observations were taken with the WR wind obscuring the line-of-sight, which could hide a colliding wind emission. Clear evidence of colliding winds was however found in the remaining six systems (WR19, 21, 31, 97, 105, 127). In WR19, increased absorption and larger emission at periastron are even detected, in line with expectations of adiabatic collisions.

accepted by MNRAS - the arxiv version has figures in low-resolution

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Cited by in corpus (4)

• Investigating 39 Galactic Wolf-Rayet stars with VLTI/GRAVITY: Uncovering A Long Period Binary Desert
• X-ray emission of massive stars and their winds
• The episodic dust-making Wolf-Rayet star HD 38030 in the Large Magellanic Cloud
• New mass estimates for massive binary systems: a probabilistic approach using polarimetric radiative transfer