The formation of the black hole in the X-ray binary system V404 Cyg |
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| Authors: | J C A Miller-Jones † P G Jonker G Nelemans S Portegies Zwart V Dhawan W Brisken E Gallo ‡ M P Rupen |
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| Institution: | NRAO Headquarters, 520 Edgemont Road, Charlottesville, VA 22903, USA;SRON, Netherlands Institute for Space Research, 3584 CA Utrecht, the Netherlands;Harvard-Smithsonian Center for Astrophysics, Cambridge, MA 02138, USA;Department of Astrophysics, IMAPP, Radboud University, Toernooiveld 1, 6525 ED, Nijmegen, the Netherlands;Astronomical Institute 'Anton Pannekoek', University of Amsterdam, Kruislaan 403, 1098 SJ Amsterdam, the Netherlands;Section Computational Science, University of Amsterdam, Kruislaan 403, 1098 SJ Amsterdam, the Netherlands;NRAO, Array Operations Center, 1003 Lopezville Road, Socorro, NM 87801, USA;Physics Department, Broida Hall, University of California, Santa Barbara, CA 93106, USA |
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| Abstract: | Using new and archival radio data, we have measured the proper motion of the black hole X-ray binary V404 Cyg to be 9.2 ± 0.3 mas yr?1 . Combined with the systemic radial velocity from the literature, we derive the full three-dimensional heliocentric space velocity of the system, which we use to calculate a peculiar velocity in the range 47–102 km s?1, with a best-fitting value of 64 km s?1. We consider possible explanations for the observed peculiar velocity and find that the black hole cannot have formed via direct collapse. A natal supernova is required, in which either significant mass (～11 M⊙) was lost, giving rise to a symmetric Blaauw kick of up to ～65 km s?1, or, more probably, asymmetries in the supernova led to an additional kick out of the orbital plane of the binary system. In the case of a purely symmetric kick, the black hole must have been formed with a mass ～9 M⊙ , since when it has accreted 0.5–1.5 M⊙ from its companion. |
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| Keywords: | astrometry stars: individual: V404 Cyg stars: kinematics stars: supernovae: general radio continuum: stars X-rays: binaries |
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