Zooming in on a sleeping giant: milliarcsecond High Sensitivity Array imaging of the black hole binary V404 Cyg in quiescence |
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| Authors: | J C A Miller-Jones † E Gallo ‡ M P Rupen A J Mioduszewski W Brisken R P Fender P G Jonker T J Maccarone |
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| Institution: | NRAO Headquarters, 520 Edgemont Road, Charlottesville, VA, 22903, USA;Physics Department, Broida Hall, University of California, Santa Barbara, CA, 93106, USA;NRAO, Array Operations Centre, 1003 Lopezville Road, Socorro, NM 87801, USA;School of Physics and Astronomy, University of Southampton, Highfield, Southampton SO17 1BJ;Astronomical Institute 'Anton Pannekoek', University of Amsterdam, Kruislaan 403, 1098 SJ, Amsterdam, the Netherlands;SRON, Netherlands Institute for Space Research, 3584 CA Utrecht, the Netherlands;Harvard–Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138, USA;Astronomical Institute, Utrecht University, 3508 TA, Utrecht, the Netherlands |
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| Abstract: | Observations of the black hole X-ray binary V404 Cyg with the very long baseline interferometer the High Sensitivity Array (HSA) have detected the source at a frequency of 8.4 GHz, providing a source position accurate to 0.3 mas relative to the calibrator source. The observations put an upper limit of 1.3 mas on the source size (5.2 au at 4 kpc) and a lower limit of 7 × 106 K on its brightness temperature during the normal quiescent state, implying that the radio emission must be non-thermal, most probably synchrotron radiation, possibly from a jet. The radio light curves show a short flare, with a rise time of ∼30 min, confirming that the source remains active in the quiescent state. |
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| Keywords: | astrometry stars: individual: V404 Cyg ISM: jets and outflows radio continuum: stars X-rays: binaries |
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