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Session 20 - All Sky Imaging Surveys of Black Hole Candidates and AGN - I.
Oral session, Tuesday, June 10
North Main Hall A,
A typical black hole X-ray nova shows a fast rise with a timescale of days and a nearly exponential decline with an e-fold of around 30 days. The optical decay is slower and the hard X-ray decay is more rapid. A "reflare" in the optical to soft X-ray band is characteristic of some sources 50 - 80 days after maximum, but this is typically when the hard power law flux is a minimum. Subsequently, the soft X-ray flux declines precipitately and the hard power law source increases to dominate the bolometric output at about 200 days and then the power fades to a finite quiescent level. Radio outbursts are common, including, in the extreme, "superluminal" jets. Other sources show repeated outbursts after the main burst and yet others have irregular light curves that do not fit this basic template. The observed exponential decay puts strong constraints on the physical nature of the accretion disk viscosity. The overall temporal behavior is discussed in terms of the fundamental physical processes, mass input from the companion, instabilities in thin disk flow, advection flows, and outflows.
