A Wolf-Rayet/black-hole X-ray binary candidate in NGC 300

Abstract

Context. Wolf Rayet/black hole binaries are believed to exist as a later evolutionary product of high-mass X-ray binaries. Hundreds of such binaries may exist in galaxies, but only a few of them are close enough to be observed as X-ray binaries. Only a couple of candidates have been reported so far. Aims. Based on XMM-Newton observations, we report the positional coincidence of the brightest X-ray source in NGC 300 (NGC 300 X-1) with a Wolf-Rayet candidate. Temporal and spectral analysis of the X-ray source is performed. Methods. We determine an accurate X-ray position of the object, and derive light curves, spectra and flux in four XMM-Newton observations. Results. The positions of the X-ray source and the helium star candidate coincide within 0.11"+-0.45". The X-ray light curves show irregular variability. During one XMM-Newton observation, the flux increased by about a factor of ten in 10 hours. The spectrum can be modelled by a power-law with Gamma~2.45 with additional relatively weak line emission, notably around 0.95 kev. The mean observed (absorbed) luminosity in the 0.2-10 kev band is ~2x10^38 erg/s. Conclusions. NGC 300 X-1 is a good candidate for a Wolf-Rayet/black-hole X-ray binary: its position coincides with a Wolf-Rayet candidate and the unabsorbed X-ray luminosity reached L(0.2-10 kev)~1x10^39 erg/s, suggesting the presence of a black hole.

4 pages, 3 figures, accepted as Letter in A&A

References in corpus (13)

• The European Photon Imaging Camera on XMM-Newton: The MOS Cameras
• The Araucaria Project. Near-Infrared Photometry of Cepheid Variables in the Sculptor Galaxy NGC 300
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• GaBoDS: The Garching-Bonn Deep Survey -- I. Anatomy of galaxy clusters in the background of NGC 300
• Chandra and HST Confirmation of the Luminous and Variable X-ray Source IC 10 X-1 as a Possible Wolf-Rayet, Black-Hole Binary
• A dozen colliding wind X-ray binaries in the star cluster R136 in the 30Doradus region
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Cited by in corpus (24)

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• Discovery of pulsations from NGC 300 ULX1 and its fast period evolution
• The Orbital Period of the Wolf-Rayet Binary IC 10 X-1; Dynamic Evidence that the Compact Object is a Black Hole
• NGC 300 X-1 is a Wolf-Rayet/Black-Hole binary
• The Hardness-Intensity Diagram of Cygnus X-3: Revisiting the Radio/X-Ray States
• Effects of the stellar wind on X-ray spectra of Cygnus X-3
• Spectral variability in Cygnus X-3
• Gemini/GNIRS infrared spectroscopy of the Wolf-Rayet stellar wind in Cygnus X-3
• A 33 hour period for the Wolf-Rayet/black hole X-ray binary candidate NGC 300 X-1
• A classification of the X-ray and radio states of Cyg X-3 and their long-term correlations
• The X-ray source content of the XMM-Newton Galactic Plane Survey
• Periodic signals from the Circinus region: two new cataclysmic variables and the ultraluminous X-ray source candidate GC X-1
• On the optical counterpart of NGC300 X-1 and the global Wolf-Rayet content of NGC300
• Discovery of a 6.4 h black hole binary in NGC 4490
• The aperiodic broad-band X-ray variability of Cygnus X-3
• NGC300 X-1 and IC10 X-1: a new breed of black hole binary?
• A broadband look at the old and new ULXs of NGC 6946
• Soft Extragalactic X-Ray Binaries at the Eddington Threshold
• Long Gamma Ray Bursts from binary black holes
• A new candidate Wolf-Rayet X-ray binary in NGC 253
• New Constraints on the Origin of the Short-Term Cyclical Variability of the Wolf-Rayet Star WR 46
• The type Ib supernova 2010O: an explosion in a Wolf-Rayet X-ray binary?
• Progenitor constraints for core-collapse supernovae from Chandra X-ray observations
• Diagnosing the Properties and Evolutionary Fates of Black Hole and Wolf-Rayet X-ray Binaries as Potential Gravitational Wave Sources for the LIGO-Virgo-KAGRA Network