Please use this identifier to cite or link to this item: http://hdl.handle.net/2381/18809
 Title: Multi-wavelength afterglow observations of the high redshift GRB 050730 Authors: Pandey, S. B.Castro-Tirado, A. J.Guerrero, M. A.Jelínek, M.De Ugarte Postigo AGorosabel, J.Guziy, S.McBreen, S.McBreen, S.Pérez-Ramírez, M. D.Combi, J. A.Bremer, M.Sota, A.Cobb, B. E.Bailyn, C. D.Muñoz-Darias, T.Guidorzi, C.Gomboc, A.Monfardini, A.Mundell, C. G.Gomboc, A.Tanvir, N.Levan, A. J.Bhatt, B. C.Sahu, D. K.Bhatt, B. C.Sahu, D. K.Sharma, S.Guziy, S.Bogdanov, O. First Published: Dec-2006 Publisher: EDP Sciences for European Southern Observatory (ESO) Citation: Astronomy & Astrophysics, 2006, 460 (2), pp. 415-424 Abstract: Context.GRB 050730 is a long duration high-redshift burst (z=3.967) that was discovered by Swift. The afterglow shows variability and was well monitored over a wide wavelength range. We present comprehensive temporal and spectral analysis of the afterglow of GRB 050730 including observations covering the wavelength range from the millimeter to X-rays. Aims.We use multi-wavelength afterglow data to understand the complex temporal and spectral decay properties of this high redshift burst. Methods.Five telescopes were used to study the decaying afterglow of GRB 050730 in the B, V, r', R, i', I, J and K photometric pass bands. A spectral energy distribution was constructed at 2.9 h post-burst in the B, V, R, I, J and K bands. X-ray data from the satellites Swift and XMM-Newton were used to study the afterglow evolution at higher energies. Results.The early afterglow shows variability at early times and the slope steepens at 0.1 days (8.6 ks) in the B, V, r', R, i', I, J and K passbands. The early afterglow light curve decayed with a powerlaw slope index $\alpha_1 = -0.60\pm0.07$ and subsequently steepened to $\alpha_2 = -1.71\pm0.06$ based on the R and I band data. A millimeter detection of the afterglow around 3 days after the burst shows an excess in comparison to theoretical predictions. The early X-ray light curve observed by Swift is complex and contains flares. At late times the X-ray light curve can be fit by a powerlaw decay with $\alpha_x = -2.5\pm0.15$ which is steeper than the optical light curve. A spectral energy distribution (SED) was constructed at ~2.9 h after the burst. An electron energy index, p, of ~2.3 was calculated using the SED and the photon index from the X-ray afterglow spectra and implies that the synchrotron cooling frequency $\nu_{\rm c}$ is above the X-ray band. DOI Link: 10.1051/0004-6361:20065010 ISSN: 0004-6361 eISSN: 1432-0746 Links: http://hdl.handle.net/2381/18809http://www.aanda.org/articles/aa/abs/2006/47/aa5010-06/aa5010-06.html Version: Publisher Version Status: Peer-reviewed Type: Journal Article Rights: Copyright © 2006 ESO. Reproduced with permission from Astronomy & Astrophysics, © ESO. Appears in Collections: Published Articles, Dept. of Physics and Astronomy

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