Swift observations of GRB050128: the early X-ray afterglow

Abstract

Swift discovered GRB050128 with the Burst Alert Telescope and promptly pointed its narrow field instruments to monitor the afterglow. X-ray observations started 108 s after the trigger time. The early decay of the afterglow is relatively flat with a temporal decay modeled with a power law with index ~ -0.3. A steepening occurs at later times (~ 1500 s) with a power law index of ~ -1.3. During this transition, the observed X-ray spectrum does not change. We interpret this behaviour as either an early jet break or evidence for a transition from the fast cooling regime to the slow cooling regime in a wind environment.

Accepted for publication on ApJL (4 pages + 3 figures)

References in corpus (2)

• Gamma-Ray Bursts: Progress, Problems & Prospects
• Swift XRT and VLT Observations of the Afterglow of GRB 041223

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