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D. A. Smith (University of Michigan), A. M. Levine, H. Bradt (MIT)
We present 2-12 keV light curves for seven GRBs observed with RXTE's All-Sky Monitor. We use data from BATSE, Ulysses, and the BeppoSAX GRBM to extend the spectral coverage of these GRBs up to hundreds of keV. Synchrotron radiation theory has been used to predict that the duration of a GRB event should scale as a power law with energy, with an index of -0.5, and evidence has been found to support this prediction (Fenimore et al. 1995; Piro et al. 1998). In the seven bursts presented here, we find that simple, singly-peaked bursts such as GRB 961002 or GRB 000301C are more likely to be consistent with a synchrotron scaling law, and complex bursts with multiple peaks such as GRB 970828 and GRB 971214 are not. Each of the two peaks of GRB 960416, treated separately, is consistent with this law. We interpret these results in the context of an internal shock scenario, in which the multiply-peaked bursts indicate that the electrons radiating at lower energies do not have time to cool before they are shocked again. An interesting exception to this trend is GRB 960727, a simple burst which shows no evidence of increasing duration at lower energies.