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.

arXiv commentaccepted by MNRAS - the arxiv version has figures in low-resolution

References in corpus (27)

• The chemical composition of the Sun
• The Transiting Exoplanet Survey Satellite
• The Man Behind the Curtain: X-rays Drive the UV through NIR Variability in the 2013 AGN Outburst in NGC 2617
• Estimating distances from parallaxes IV: Distances to 1.33 billion stars in Gaia Data Release 2
• The generalised Lomb-Scargle periodogram. A new formalism for the floating-mean and Keplerian periodograms
• Kepler Mission Design, Realized Photometric Performance, and Early Science
• A new calibration of stellar parameters of Galactic O stars
• The Galactic WC stars: Stellar parameters from spectral analyses indicate a new evolutionary sequence
• The Galactic WC and WO stars: The impact of revised distances from Gaia DR2 and their role as massive black hole progenitors
• The Galactic WN stars revisited. Impact of Gaia distances on fundamental stellar parameters
• A Simple Scaling Analysis of X-ray Emission and Absorption in Hot-Star Winds
• The Conspicuous Absence of X-ray Emission from Carbon-Enriched Wolf-Rayet Stars
• X-ray emission from interacting massive binaries: a review of 15 years of progress
• Thin-shell mixing in radiative wind-shocks and the Lx-Lbol scaling of O-star X-rays
• HD148937: a multiwavelength study of the third Galactic member of the Of?p class
• Suppression of X-rays from radiative shocks by their thin-shell instability
• Radio Properties of Pinwheel Nebulae
• Can single O stars produce non-thermal radio emission?
• X-rays from Colliding Stellar Winds: the case of close WR+O binary systems
• Observations of Binary and Single Wolf-Rayet Stars with XMM-Newton and Chandra
• V444 Cyg X-ray and polarimetric variability: Radiative and Coriolis forces shape the wind collision region
• The X-ray light curve of the massive colliding wind Wolf-Rayet + O binary WR21a
• Disentangling the Nature of the Radio Emission in Wolf Rayet Stars
• Dust formation by the colliding-wind WC5+O9 binary WR19 at periastron passage
• High-resolution X-ray spectroscopy of the magnetic Of?p star HD148937
• Long-term soft and hard X-ray investigation of the colliding wind WN+O binary WR 25
• The orbit of the double-lined Wolf-Rayet Binary HDE 318016 (= WR98)

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