1. SwiftPanchromatic Observations of the Bright Gamma‐Ray Burst GRB 050525a
- Author
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A. J. Blustin, D. Band, S. Barthelmy, P. Boyd, M. Capalbi, S. T. Holland, F. E. Marshall, K. O. Mason, M. Perri, T. Poole, P. Roming, S. Rosen, P. Schady, M. Still, B. Zhang, L. Angelini, L. Barbier, A. Beardmore, A. Breeveld, D. N. Burrows, J. R. Cummings, J. Canizzo, S. Campana, M. M. Chester, G. Chincarini, L. R. Cominsky, A. Cucchiara, M. de Pasquale, E. E. Fenimore, N. Gehrels, P. Giommi, M. Goad, C. Gronwall, D. Grupe, J. E. Hill, D. Hinshaw, S. Hunsberger, K. C. Hurley, M. Ivanushkina, J. A. Kennea, H. A. Krimm, P. Kumar, W. Landsman, V. La Parola, C. B. Markwardt, K. McGowan, P. Meszaros, T. Mineo, A. Moretti, A. Morgan, J. Nousek, P. T. O’Brien, J. P. Osborne, K. Page, M. J. Page, D. M. Palmer, A. M. Parsons, J. Rhoads, P. Romano, T. Sakamoto, G. Sato, G. Tagliaferri, J. Tueller, A. A. Wells, and N. E. White
- Subjects
Physics ,Jet (fluid) ,Astrophysics::High Energy Astrophysical Phenomena ,Astrophysics (astro-ph) ,FOS: Physical sciences ,Flux ,Astronomy and Astrophysics ,Astrophysics::Cosmology and Extragalactic Astrophysics ,Astrophysics ,Light curve ,Power law ,Redshift ,Afterglow ,Interstellar medium ,Space and Planetary Science ,Gamma-ray burst - Abstract
The bright gamma-ray burst GRB050525a has been detected with the Swift observatory, providing unique multiwavelength coverage from the very earliest phases of the burst. The X-ray and optical/UV afterglow decay light curves both exhibit a steeper slope ~0.15 days after the burst, indicative of a jet break. This jet break time combined with the total gamma-ray energy of the burst constrains the opening angle of the jet to be 3.2 degrees. We derive an empirical `time-lag' redshift from the BAT data of z_hat = 0.69 +/- 0.02, in good agreement with the spectroscopic redshift of 0.61. Prior to the jet break, the X-ray data can be modelled by a simple power law with index alpha = -1.2. However after 300 s the X-ray flux brightens by about 30% compared to the power-law fit. The optical/UV data have a more complex decay, with evidence of a rapidly falling reverse shock component that dominates in the first minute or so, giving way to a flatter forward shock component at later times. The multiwavelength X-ray/UV/Optical spectrum of the afterglow shows evidence for migration of the electron cooling frequency through the optical range within 25000 s. The measured temporal decay and spectral indices in the X-ray and optical/UV regimes compare favourably with the standard fireball model for Gamma-ray bursts assuming expansion into a constant density interstellar medium., Comment: 31 pages, 7 figures, referee comments implemented, typo corrected in author list, accepted by ApJ
- Published
- 2006
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