Extensive multiband study of the X-ray rich GRB 050408. A likely off-axis event with an intense energy injection

Aims. Understand the shape and implications of the multiband light curve of GRB 050408, an X-ray rich (XRR) burst. Methods. We present a multiband optical light curve, covering the time from the onset of the gamma-ray event to several months after, when we only detect the host galaxy. Together with...

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Published inarXiv.org
Main Authors A de Ugarte Postigo, Fatkhullin, T A, Johannesson, G, Gorosabel, J, Sokolov, V V, Castro-Tirado, A J, Yu Yu Balega, Spiridonova, O I, Jelinek, M, Guziy, S, Perez-Ramirez, D, Hjorth, J, Laursen, P, Bersier, D, Pandey, S B, Bremer, M, Monfardini, A, Huang, K Y, Urata, Y, Ip, W H, Tamagawa, T, Kinoshita, D, Mizuno, T, Arai, Y, Yamagishi, H, Soyano, T, Usui, F, Tashiro, M, Abe, K, Onda, K, Aslan, Z, Khamitov, I, Ozisik, T, Kiziloglu, U, Bikmaev, I, Sakhibullin, N, Burenin, R, Pavlinsky, M, Sunyaev, R, Bhattacharya, D, Kamble, A P, Chandra, C H Ishwara, Trushkin, S A
Format Paper
LanguageEnglish
Published Ithaca Cornell University Library, arXiv.org 19.12.2006
Subjects
Galaxies
Gamma ray bursts
Gamma rays
Light curve
Organic chemistry
Radio observation
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Summary:Aims. Understand the shape and implications of the multiband light curve of GRB 050408, an X-ray rich (XRR) burst. Methods. We present a multiband optical light curve, covering the time from the onset of the gamma-ray event to several months after, when we only detect the host galaxy. Together with X-ray, millimetre and radio observations we compile what, to our knowledge, is the most complete multiband coverage of an XRR burst afterglow to date. Results. The optical and X-ray light curve is characterised by an early flattening and an intense bump peaking around 6 days after the burst onset. We explain the former by an off-axis viewed jet, in agreement with the predictions made for XRR by some models, and the latter with an energy injection equivalent in intensity to the initial shock. The analysis of the spectral flux distribution reveals an extinction compatible with a low chemical enrichment surrounding the burst. Together with the detection of an underlying starburst host galaxy we can strengthen the link between XRR and classical long-duration bursts.
ISSN:2331-8422
DOI:10.48550/arxiv.0612545