The First Simultaneous X-Ray/Radio Detection of the First Be/BH System MWC 656

Abstract

MWC 656 is the first known Be/black hole (BH) binary system. Be/BH binaries are important in the context of binary system evolution and sources of detectable gravitational waves because they are possible precursors of coalescing neutron star/BH binaries. X-ray observations conducted in 2013 revealed that MWC 656 is a quiescent high-mass X-ray binary (HMXB), opening the possibility to explore X-ray/radio correlations and the accretion/ejection coupling down to low luminosities for BH HMXBs. Here we report on a deep joint Chandra/VLA observation of MWC 656 (and contemporaneous optical data) conducted in 2015 July that has allowed us to unambiguously identify the X-ray counterpart of the source. The X-ray spectrum can be fitted with a power law with $\Gamma \sim 2$, providing a flux of $\simeq 4\times 10^{-15}$ erg cm${}^{-2}$ s${}^{-1}$ in the 0.5-8 keV energy range and a luminosity of $L_{\mathrm{X}}\simeq 3\times 10^{30}$ erg s${}^{-1}$ at a 2.6 kpc distance. For a 5 M${}_{\odot }$ BH this translates into $\simeq 5\times 10^{-9}$ $L_{\mathrm{Edd}}$. These results imply that MWC 656 is about 7 times fainter in X-rays than it was two years before and reaches the faintest X-ray luminosities ever detected in stellar-mass BHs. The radio data provide a detection with a peak flux density of $3.5\pm 1.1$ $\mu$Jy beam${}^{-1}$. The obtained X-ray/radio luminosities for this quiescent BH HMXB are fully compatible with those of the X-ray/radio correlations derived from quiescent BH low-mass X-ray binaries. These results show that the accretion/ejection coupling in stellar-mass BHs is independent of the nature of the donor star.

arXiv comment6 pages, 4 figures. Accepted for publication in ApJ Letters

References in corpus (37)

• Astropy: A Community Python Package for Astronomy
• X-ray Properties of Black-Hole Binaries
• The USNO-B Catalog
• Gaia Data Release 1. Summary of the astrometric, photometric, and survey properties
• The VizieR database of Astronomical Catalogues
• Towards a unified model for black hole X-ray binary jets
• Sources of Relativistic Jets in the Galaxy
• The MAXI Mission on the ISS: Science and Instruments for Monitoring All Sky X-Ray Images
• A universal radio/X-ray correlation in low/hard state black hole binaries
• Multi-Scale CLEAN deconvolution of radio synthesis images
• Powerful jets from black hole X-ray binaries in Low/Hard X-ray states
• Radio / X-ray correlation in the low/hard state of GX 339--4
• GRS 1915+105 and the Disc-Jet Coupling in Accreting Black Hole Systems
• Stellar Radio Astronomy. Probing Stellar Atmospheres from Protostars to Giants
• The "universal" radio/X-ray flux correlation : the case study of the black hole GX 339-4
• Exploring the Role of Jets in the Radio/X-ray Correlations of GX339-4
• A radio-emitting outflow in the quiescent state of A0620-00: implications for modelling low-luminosity black hole binaries
• A Be-type star with a black hole companion
• The X-ray Spectral Evolution of Galactic Black Hole X-ray Binaries Toward Quiescence
• The radio/X-ray domain of black hole X-ray binaries at the lowest radio luminosities
• Assessing luminosity correlations via cluster analysis: Evidence for dual tracks in the radio/X-ray domain of black hole X-ray binaries
• On the Apparent Lack of Be X-ray Binaries with Black Holes
• On the binary nature of the gamma-ray sources AGL J2241+4454 (=MWC 656) and HESS J0632+057 (=MWC 148)
• Multi-Scale CLEAN: A comparison of its performance against classical CLEAN in galaxies using THINGS
• A deep radio survey of hard state and quiescent black hole X-ray binaries
• The balance of power: accretion and feedback in stellar mass black holes
• The Be Star HD 215227: A Candidate Gamma-ray Binary
• On the formation and evolution of the first Be star in a black hole binary MWC 656
• The structure of the jet in Cyg X-1 inferred from orbital modulation of the radio emission
• A Clean Sightline to Quiescence: Multiwavelength Observations of the High Galactic Latitude Black Hole X-ray Binary Swift J1357.2-0933
• Discovery of X-ray emission from the first Be/black hole system
• Radio Emission from the Be/Black Hole Binary MWC 656
• MAGIC observations of MWC 656, the only known Be/BH system
• The gamma-ray source AGL J2241+4454 as the possible counterpart of MWC 656
• Telescope Fabra ROA Montsec: a new robotic wide-field Baker-Nunn facility
• An updated gamma-ray analysis of the Be-BH binary HD~215227
• Non-thermal emission from high-energy binaries through interferometric radio observations

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• Radio & X-ray detections of GX 339--4 in quiescence using MeerKAT and Swift
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• Radio Variability from a Quiescent Stellar Mass Black Hole Jet
• Observations of the Disk/Jet Coupling of MAXI J1820+070 During its Descent to Quiescence
• On the Neutron Star/Black Hole Mass Gap and Black Hole Searches
• Optical Precursors to Black Hole X-ray Binary Outbursts: An evolving synchrotron jet spectrum in Swift J1357.2-0933
• A radio frequency study of the accreting millisecond X-ray pulsar, IGR J16597$-$3704, in the globular cluster NGC 6256
• The boring history of Gaia BH3 from isolated binary evolution
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• Observations of the Ultra-compact X-ray Binary 4U 1543-624 in Outburst with NICER, INTEGRAL, Swift, and ATCA
• Hubble spectroscopy of LB-1: comparison with B+black-hole and Be+stripped-star models
• GS 2000+25: The Least Luminous Black Hole X-ray Binary
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• Whispering in the dark: Faint X-ray emission from black holes with OB star companions
• ALMA observations of A0620-00: fresh clues on the nature of quiescent black hole X-ray binary jets
• An Overview of Compact Star Populations and Some of Its Open Problems
• Optical spectroscopy of the Be/black hole binary MWC656 -- interaction of a black hole with a circumstellar disc
• Radius, rotational period and inclination of the Be stars in the Be/gamma-ray binaries MWC 148 and MWC 656
• The flickering radio jet from the quiescent black hole X-ray binary A0620-00
• Accretion Disc-Jet Couplings in X-ray Binaries
• Ultraviolet spectroscopy reveals a hot and luminous companion to the Be star+black hole candidate MWC 656
• The black hole X-ray binary MAXI J1348$-$630 in quiescence