Optical spectroscopy of the Be/black hole binary MWC656 -- interaction of a black hole with a circumstellar disc

Abstract

We present new spectroscopic observations of the Be/black hole binary MWC 656 obtained during the period 2015 - 2021. We measure the equivalent width of H$\alpha$ (EW${}_{\alpha }$), H$\beta$ ($E{W}_{\beta }$), and the distance between the peaks of H$\alpha$ ($\Delta V_{\alpha }$), H$\beta$ ($\Delta V_{\beta }$), and FeII ($\Delta V_{FeII}$) lines. Combining new and old data, we find that: - the density of the circumstellar disc of MWC 656 ($\Delta V_{\alpha }$ versus $E{W}_{\alpha }$ diagram) is similar to the Be stars. For the Be stars we find the relation $\Delta V_{\beta }=0.999\Delta V_{\alpha }+62.4$ km s${}^{-1}$, and the position of MWC~656 corresponds to the average behaviour of the Be stars. This means that the presence of the black hole does not change the overall structure of the circumstellar disc. - the periodogram analysis indicates modulation of $E{W}_{\alpha }$ with a period $60.4\pm 0.4$ days, which is identical to the binary orbital period. The maxima of $E{W}_{\alpha }$ and $E{W}_{\beta }$ are around periastron (phase zero). - around orbital phase zero, $\Delta V_{\beta }$ and $\Delta V_{FeII}$ decrease by about $30$ km s${}^{-1}$. This suggests that we observe an increase of the circumstellar disc size induced by the periastron passage of the black hole and that the entire circumstellar disc pulsates with the orbital period with relative amplitude of 10-20%. The observations also indicate, that the reason for the black hole in MWC 656 to be in deep quiescence is a very low efficiency of accretion ($\sim 2\times 10^{-6}$).

arXiv commentAccepted by Astronomische Nachrichten / Astronomical Notes

References in corpus (45)

• The Astropy Project: Building an inclusive, open-science project and status of the v2.0 core package
• Estimating distances from parallaxes. V: Geometric and photogeometric distances to 1.47 billion stars in Gaia Early Data Release 3
• Be/X-ray binaries
• Classical Be Stars: Rapidly Rotating B Stars with Viscous Keplerian Decretion Disks
• A natural explanation for periodic X-ray outbursts in Be/X-ray binaries
• Constraint on the maximum mass of neutron stars using GW170817 event
• A 2.1 Solar Mass Pulsar Measured by Relativistic Orbital Decay
• A Be-type star with a black hole companion
• Viscous Effects on the Interaction between the Coplanar Decretion Disc and the Neutron Star in Be/X-Ray Binaries
• Recent Progress in Neutron Star Theory
• Orbital Parameters of the Microquasar LSI +61 303
• The X-ray Spectral Evolution of Galactic Black Hole X-ray Binaries Toward Quiescence
• The Orbits of the Gamma-ray Binaries LS I +61 303 and LS 5039
• Astrophysical parameters of LS2883 and implications for the PSR B1259-63 gamma-ray binary
• The life cycles of Be viscous decretion discs: fundamental disc parameters of 54 SMC Be stars
• The kinematics and orbital dynamics of the PSR B1259$-$63/LS 2883 system from 23 years of pulsar timing
• FUV Detection of the Suspected Subdwarf Companion to the Be Star 59 Cygni
• The life cycles of Be viscous decretion discs: time-dependent modelling of infrared continuum observations
• The first determination of the viscosity parameter in the circumstellar disk of a Be Star
• On the binary nature of the gamma-ray sources AGL J2241+4454 (=MWC 656) and HESS J0632+057 (=MWC 148)
• Multi-wavelength Observations of the Binary System PSR B1259-63/LS~2883 around the 2014 Periastron Passage
• The geometric distance and binary orbit of PSR B1259-63
• Orbital periods of cataclysmic variables identified by the SDSS. III. Time-series photometry obtained during the 2004/5 International Time Project on La Palma
• Supernova Kicks and Misaligned Be Star Binaries
• Population Synthesis of Black Hole X-Ray Binaries
• A 0535+26: Back in business
• On the relationship between circumstellar disc size and X-ray outbursts in Be/X-ray binaries
• The First Simultaneous X-Ray/Radio Detection of the First Be/BH System MWC 656
• The Be Star HD 215227: A Candidate Gamma-ray Binary
• The Black Hole Candidate LSI+61303
• Discovery of X-ray emission from the first Be/black hole system
• Spectroscopic atlas of Halpha and Hbeta in a sample of northern Be stars
• H-alpha observations of the gamma-ray-emitting Be/X-ray binary LSI+61303: orbital modulation, disk truncation, and long-term variability
• Radio Emission from the Be/Black Hole Binary MWC 656
• Orbital variability of the optical linear polarization of the $\gamma$-ray binary LS I +61 303 and new constraints on the orbital parameters
• Optical spectroscopy of Be/gamma-ray binaries
• An application of the Ghosh & Lamb model to the accretion powered X-ray pulsar X Persei
• The Liverpool Telescope Spectrograph: FRODOSpec
• Tidal Disruption of Inclined or Eccentric Binaries by Massive Black Holes
• MAGIC observations of MWC 656, the only known Be/BH system
• Spectral observations of X Persei: Connection between H-alpha and X-ray emission
• Modelling the correlated keV/TeV light curves of Be/gamma-ray binaries
• Radius, rotational period and inclination of the Be stars in the Be/gamma-ray binaries MWC 148 and MWC 656
• Optical and Near-Infrared Monitoring of Gamma-ray Binaries Hosting Be Stars
• Near-infrared Brightening around the Periastron Passages of the Gamma-ray Binary PSR B1259$-$63 /LS 2883

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