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Halpha flares from V404 Cyg in quiescence

Halpha flares from V404 Cyg in quiescence
Halpha flares from V404 Cyg in quiescence
We present a spectrophotometric study of short-term optical variability in the quiescent black hole X-ray transient V404 Cyg. This includes two nights of high-time-resolution Ha spectroscopy with which we resolve much of the time variability, and a further six nights of archival spectroscopy with lower time resolution but higher spectral resolution. We find significant variability in most of the data considered, with both the Haline and the continuum often varying in a correlated way. This includes both dramatic flares lasting a few hours in which the line flux nearly doubles and lower-level flickering. The strongest flares involve development of asymmetry in the line profile, with the red wing usually strongest independent of orbital phase. It is unclear why this is the case, but we discuss several possible explanations. We consider the energetics of the flares and compare with plausible models including chromospheric activity on the companion star, local magnetic reconnection events within the disc and varying irradiation from close to the black hole. Based on the line profile changes during the flares, we conclude that the most likely origin for the variability is variable photoionization by the central source, although local flares within the disc cannot be ruled out.
accretion, accretion discs, binaries, close, stars, individual, V404 Cyg
0035-8711
1009-1021
Hynes, R.I
ee3ac511-21b3-43d6-a500-0ae13ba28965
Zurita, C.
a54c6c5c-a599-4550-8596-050d925a0241
Haswell, C.A.
f90b3ff8-634b-4b26-8b84-d9d6863622ba
Casares, J
b36492e0-a175-4960-9634-3e64a01fc5ac
Charles, P.A.
0429b380-0754-4dc1-8def-885c7fa6a086
Pavlenko, E.P.
8ec638a3-4fff-4fae-b70f-1ea8a9c5c131
Shugarov, S.Y.
f1d1c560-6d76-4a14-b7e5-851527ec191c
Lott, D.A.
f8ee64df-6f9d-4093-ab53-c34dd74585bd
Hynes, R.I
ee3ac511-21b3-43d6-a500-0ae13ba28965
Zurita, C.
a54c6c5c-a599-4550-8596-050d925a0241
Haswell, C.A.
f90b3ff8-634b-4b26-8b84-d9d6863622ba
Casares, J
b36492e0-a175-4960-9634-3e64a01fc5ac
Charles, P.A.
0429b380-0754-4dc1-8def-885c7fa6a086
Pavlenko, E.P.
8ec638a3-4fff-4fae-b70f-1ea8a9c5c131
Shugarov, S.Y.
f1d1c560-6d76-4a14-b7e5-851527ec191c
Lott, D.A.
f8ee64df-6f9d-4093-ab53-c34dd74585bd

Hynes, R.I, Zurita, C., Haswell, C.A., Casares, J, Charles, P.A., Pavlenko, E.P., Shugarov, S.Y. and Lott, D.A. (2002) Halpha flares from V404 Cyg in quiescence. Monthly Notices of the Royal Astronomical Society, 330 (4), 1009-1021. (doi:10.1046/j.1365-8711.2002.05145.x).

Record type: Article

Abstract

We present a spectrophotometric study of short-term optical variability in the quiescent black hole X-ray transient V404 Cyg. This includes two nights of high-time-resolution Ha spectroscopy with which we resolve much of the time variability, and a further six nights of archival spectroscopy with lower time resolution but higher spectral resolution. We find significant variability in most of the data considered, with both the Haline and the continuum often varying in a correlated way. This includes both dramatic flares lasting a few hours in which the line flux nearly doubles and lower-level flickering. The strongest flares involve development of asymmetry in the line profile, with the red wing usually strongest independent of orbital phase. It is unclear why this is the case, but we discuss several possible explanations. We consider the energetics of the flares and compare with plausible models including chromospheric activity on the companion star, local magnetic reconnection events within the disc and varying irradiation from close to the black hole. Based on the line profile changes during the flares, we conclude that the most likely origin for the variability is variable photoionization by the central source, although local flares within the disc cannot be ruled out.

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More information

Published date: 2002
Keywords: accretion, accretion discs, binaries, close, stars, individual, V404 Cyg

Identifiers

Local EPrints ID: 38005
URI: http://eprints.soton.ac.uk/id/eprint/38005
ISSN: 0035-8711
PURE UUID: c7364b17-ade5-489e-b034-15d58452b8b0

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Date deposited: 30 May 2006
Last modified: 15 Jul 2019 19:03

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Contributors

Author: R.I Hynes
Author: C. Zurita
Author: C.A. Haswell
Author: J Casares
Author: P.A. Charles
Author: E.P. Pavlenko
Author: S.Y. Shugarov
Author: D.A. Lott

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