Swift Panchromatic Observations of the Bright Gamma-Ray Burst GRB 050525a

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. BurrowsJ.~R. Cummings, J. Cannizzo, 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. Mészáros, 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, N.~E. White

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The bright gamma-ray burst GRB 050525a 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 3fdg2. We derive an empirical "time-lag" redshift from the BAT data of img1.gif = 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 modeled by a simple power law with index α = -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 25,000 s. The measured temporal decay and spectral indexes in the X-ray and optical/UV regimes compare favorably with the standard fireball model for gamma-ray bursts assuming expansion into a constant-density interstellar medium.
Original languageEnglish
Pages (from-to)901-913
Number of pages13
JournalAstrophysical Journal
Issue number2
Publication statusPublished - 1 Feb 2006


  • Astrometry, Galaxies: Distances and Redshifts, Gamma Rays: Bursts, Shock Waves, X-rays: individual (GRB 050525a), Astrophysics

Cite this

Blustin, A. J., Band, D., Barthelmy, S., Boyd, P., Capalbi, M., Holland, S. T., Marshall, F. E., Mason, K. O., Perri, M., Poole, T., Roming, P., Rosen, S., Schady, P., Still, M., Zhang, B., Angelini, L., Barbier, L., Beardmore, A., Breeveld, A., ... White, N. E. (2006). Swift Panchromatic Observations of the Bright Gamma-Ray Burst GRB 050525a. Astrophysical Journal, 637(2), 901-913. https://doi.org/10.1086/498425