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Dual Nature of Hard X-Ray Outbursts from the Superluminal X-Ray Transient Source GRO J1655-40

M. Tavani·A. Fruchter·S. N. Zhang·B. A. Harmon·R. N. Hjellming·M. P. Rupen·C. Bailyn·M. Livio
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Abstract

We report the results of multiwavelength observations of the superluminal X-ray transient GRO J1655-40 during and following the prominent hard X-ray outburst of March-April 1995. GRO J1655-40 was continuously monitored by BATSE on board CGRO, and repeatedly observed in the radio and optical bands from the ground. About a month after the onset of the hard X-ray outburst, GRO J1655-40 was observed twice by HST on April 25 and 27 1995, with the aim of detecting faint optical emission from ejected plasmoids. Despite the similarity of the hard X-ray emission in April 1995 with previous events in 1994, no radio or optical emission related to plasmoids was detected. We conclude that GRO J1655-40 is subject to a complex behavior showing: radio-loud hard X-ray outbursts with strong radio emission (of flux $f_r \goe 100$~mJy) both from a `core' source and from propagating plasmoids (as those in 1994), and radio-quiet hard X-ray outbursts with no detectable radio emission and plasmoid activity ($f_r \loe 0.5$~mJy) (as those in 1995). Our results can constrain models of particle acceleration and radiation of relativistic plasmoids.

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M. Tavani, A. Fruchter, S. N. Zhang, B. A. Harmon, R. N. Hjellming, M. P. Rupen, C. Bailyn, M. Livio. 1996-10-25. Dual Nature of Hard X-Ray Outbursts from the Superluminal X-Ray Transient Source GRO J1655-40. https://doi.org/10.1086/310406

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