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R.E. Rothschild, W.A. Heindl (CASS/UCSD)
The 1996-1997 outbursts of the microquasar GRO J1655-40 were monitored by the Rossi X-ray Timing Explorer (RXTE) in a series of 80 pointed observations. During this time, both the Very High and High/Soft emission states were observed. In 1997 the High/Soft state hard x-ray flux (>20 keV) vanished on at least 5 occasions with an ~20 day timescale between disappearances. One prolonged disappearance was seen to last 30 days, while the others recovered within ~10 days. Compton up-scattering of soft x-rays from the inner accretion disk by a hot corona is believed to be the origin of the hard x-ray flux. The observed hard x-ray variability suggests recurrent loss of the corona.
The author(s) of this abstract have provided an email address for comments about the abstract: rrothschild@ucsd.edu