Mon. Not. R. Astron. Soc., 401, 1255-1263 (2010/January-2)
Following the 2008 outburst decay of the black hole candidate H 1743-322in X-ray and radio.
JONKER P.G., MILLER-JONES J., HOMAN J., GALLO E., RUPEN M., TOMSICK J., FENDER R.P., KAARET P., STEEGHS D.T.H., TORRES M.A.P., WIJNANDS R., MARKOFF S. and LEWIN W.H.G.
Abstract (from CDS):
In this paper, we report on radio (Very Large Array and Austrialian Telescope Compact Array) and X-ray (RXTE, Chandra and Swift) observations of the outburst decay of the transient black hole candidate H 1743-322in early 2008. We find that the X-ray light curve followed an exponential decay, levelling off towards its quiescent level. The exponential decay time-scale is ~4 days and the quiescent flux corresponds to a luminosity of erg/s. This together with the relation between quiescent X-ray luminosity and orbital period reported in the literature suggests that H 1743-322 has an orbital period longer than ~10 h. Both the radio and X-ray light curve show evidence for flares. The radio-X-ray correlation can be well described by a power-law with index ~0.18. This is much lower than the index of ~0.6-0.7 found for the decay of several black hole transients before. The radio spectral index measured during one of the radio flares while the source is in the low-hard state is -0.5±0.15, which indicates that the radio emission is optically thin. This is unlike what has been found before in black hole sources in the low-hard state. We attribute the radio flares and the low index for the radio-X-ray correlation to the presence of shocks downstream the jet flow, triggered by ejection events earlier in the outburst. We find no evidence for a change in X-ray power-law spectral index during the decay, although the relatively high extinction of NH~ 2.3 x 1022/cm2 limits the detected number of soft photons and thus the accuracy of the spectral fits.
© 2009 The Authors. Journal compilation © 2009 RAS
accretion, accretion discs - binaries - stars: individual: H 1743-322 - X-rays: binaries
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