Title:	Extensive mutiband study of the X-ray rich GRB 050408: A likely off-axis event with an intense energy injection
Authors:	de Ugarte, Postigo A. Fatkhullin, T.A. Bhattacharya, D. Kamble, Atish P. +39 Co-authors
Keywords:	gamma rays: bursts techniques: photometric
Issue Date:	Feb-2007
Publisher:	EDP Sciences
Citation:	Astronomy and Astrophysics, 2007, Vol.462, pL57-L60
Abstract:	Aims.Understand the shape and implications of the multiband ligth 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 γ-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. Based on observations collected at SAO, La Silla, Roque de los Muchachos, Haleakala, Kitt Peak, Cerro Tololo, TÜBITAK, Kiso, Observatorio de Sierra Nevada, Plateau du Bure, GMRT and RATAN-600. Appendices A and B are only available in electronic form at http://www.aanda.org
Description:	Open Access.
URI:	http://hdl.handle.net/2289/2210
Alternative Location:	http://adsabs.harvard.edu/cgi-bin/bib_query?2007A&A...462L..57D http://arxiv.org/abs/astro-ph/0612545 http://dx.doi.org/10.1051/0004-6361:20066660
Copyright:	2007 EDP Sciences
Appears in Collections:	Research Papers (A&A)

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