Variability of the Optical Emission from Black Hole Accretion Disks and Jets(Poster)

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We report on our optical observations of black hole X-ray transients (BHXTs) and gamma-ray bursts (GRBs), which were obtained by the VSNET (Variable Star Network) Collaboration. The BHXT V4641 Sgr has been one of main campaign targets since 1999, when it experienced a short super-Eddington outburst. Our observation revealed an anti-correlation between the optical and X-ray flux during the outburst in 1999 September. It implies the formation of an optically thick cloud which absorbed the X-ray flux and reemitted in the optical range. V4641 Sgr again entered an active phase in 2002 May. During this active phase, repetitive short (0.1 d) flares were detected with non-thermal rapid optical fluctuations, which presumably originated from an inner region of the accretion flow. As well as BHXTs, we have performed prompt observations of GRB afterglows. Our observations of the afterglow of GRB030329 revealed a few hours variations on a power-law decay component. These variations may have occurred due to energy variations in the forward shock region of a blast wave.
理論物理学刊行会の論文
2004-11-15