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The early- and late-time spectral and temporal evolution of ORB 050716

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journal contribution
posted on 24.10.2012, 09:06 by E. Rol, J. P. Osborne, K. L. Page, A. P. Beardmore, P. T. O'Brien, N. R. Tanvir, N. P. Bannister, K. E. McGowan, A. J. Levan, N. R Tanvir, D. Bersier, A. S. Fruchter, C. Guidorzi, A. Monfardini, A. Gomboc, F. Marshall, S. Barthelmy
We report on a comprehensive set of observations of gamma-ray burst 050716, detected by the Swift satellite and subsequently followed-up rapidly in X-ray, optical and near-infrared (NIR) wavebands. The prompt emission is typical of long-duration bursts, with two peaks in a time interval of T90= 68 s (15–350 keV). The prompt emission continues at lower flux levels in the X-ray band, where several smaller flares can be seen on the top of a decaying light curve that exhibits an apparent break around 220 s post-trigger. This temporal break is roughly coincident with a spectral break. The latter can be related to the extrapolated evolution of the break energy in the prompt γ-ray emission, and is possibly the manifestation of the peak flux break frequency of the internal shock passing through the observing band. A possible 3σ change in the X-ray absorption column is also seen during this time. The late-time afterglow behaviour is relatively standard, with an electron distribution power-law index of p= 2; there is no notable temporal break out to at least 10 d. The broad-band optical/NIR to X-ray spectrum indicates a redshift of z≳ 2 for this burst, with a host-galaxy extinction value of EB−V≈ 0.7 that prefers a small magellanic cloud (SMC)-like extinction curve.



Monthly Notices of the Royal Astronomical Society, 2007, 374 (3), pp. 1078-1084


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