The 2003 Outburst of the Galactic Microquasar V4641 Sgr (=SAX J1819.3-2525)

摘要

The black hole candidate V4641 Sgr (=SAX J1819.3-2525) went through a brief outburst during 2003 Aug 01 to Aug 08. During the outburst, activity was noted in optical, radio as well as X-rays. We report results of our X-ray spectral analysis and simultaneous X-ray and optical observations of the source during this outburst. Characteristics of the observed X-ray spectral energy distribution is discussed. The spectral results suggest occasional outflow/mass ejection and an obscured accretion disk. Simultaneous X-ray and optical R band lightcurves show strong correlation and the optical lags the X-rays, which can be explained if the origin of the optical emission is attributed to reprocessing of X-rays at the outer regions of the accretion disk.