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dc.contributor.authorUemura, Makoto
dc.contributor.authorKato, Taichi
dc.contributor.authorIshioka, Ryoko
dc.contributor.authorTanabe, Kenji
dc.contributor.authorTorii, Ken
dc.contributor.authorSantallo, Roland
dc.contributor.authorMonard, Berto
dc.contributor.authorMarkwardt, Craig
dc.contributor.authorSwank, Jean
dc.contributor.authorSault, Robert
dc.contributor.authorMacquart, Jean-Pierre
dc.contributor.authorLinnolt, Michael
dc.contributor.authorKiyoto, Seiichiro
dc.contributor.authorStubbings, Rod
dc.contributor.authorNelson, Peter
dc.contributor.authorRichards, Tom
dc.contributor.authorBailyn, Charles
dc.contributor.authorWest, Doug
dc.contributor.authorMasi, Gianluca
dc.contributor.authorMiyashita, Atsushi
dc.contributor.authorSano, Yasuo
dc.contributor.authorScarmato, Toni
dc.identifier.citationUemura, Makoto and Kato, Taichi and Ishioka, Ryoko and Tanabe, Kenji and Torii, Ken and Santallo, Roland and Monard, Berto and Markwardt, Craig and Swank, Jean and Sault, Robert and Macquart, Jean-pierre and Linnolt, Michael and Kiyoto, Seiichiro and Stubbings, Rod and Nelson, Peter and Richards, Tom and Bailyn, Charles and West, Doug and Masi, Gianluca and Miyashita, Atsushi and Sano, Yasuo and Scarmato, Toni. 2003. Outburst and Post-Outburst Active Phase of the Black Hole X-Ray Binary V4641 Sagittarii in 2002. Publications of Astronomical Society of Japan. 56 (SP1): pp. S61-S75.

The black hole X-ray binary V4641 Sgr experienced an outburst in 2002 May, which was detected at X-ray, optical, and radio wavelengths. The outburst lasted for only 6 days, but the object remained active for the next several months. Here, we report on the detailed properties of light curves during the outburst and the post-outburst active phase. We reveal that rapid optical variations of -100s became more prominent when a thermal flare weakened and the optical spectrum flattened in the Ic, Rc, and V-band regions. In conjunction with the flat spectrum in the radio range, this strongly indicates that the origin of rapid variations is not thermal emission, but synchrotron emission. Just after the outburst, we detected repeated flares at optical and X-ray wavelengths. The optical and X-ray light curves exhibited a strong correlation with the X-rays lagging by about 7min. The X-ray lag can be understood in terms of a hot region propagating into the inner region of the accretion flow. The short X-ray lag, however, requires modifications of this simple scenario to account for the short propagation time. We also detected high-amplitude rapid variations 50 days after the outburst, which we call optical flashes. During the most prominent optical flash, the object brightened by 1.2mag only within 30s. The released energy indicates that the emission source should be at the innermost region of the accretion flow. (author abst.)

dc.publisherNihon Tenmon Gakkai
dc.titleOutburst and Post-Outburst Active Phase of the Black Hole X-Ray Binary V4641 Sagittarii in 2002
dc.typeJournal Article
dcterms.source.titlePublications of Astronomical Society of Japan
curtin.accessStatusOpen access
curtin.facultyFaculty of Science and Engineering
curtin.facultyCurtin Institute of Radio Astronomy

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