http://arxiv.org/abs/1408.3042
For a sample of Swift and Fermi GRBs, we show that the minimum variability timescale for the prompt emission is related to the bulk Lorentz factor in a complex manner: For small $\Gamma$’s, the variability timescale exhibits a shallow (plateau) region. For large $\Gamma$’s, the variability timescale declines steeply as a function of $\Gamma$ ($\delta T\propto\Gamma^{-4.05\pm0.64}$). Evidence is also presented for an intriguing correlation between the peak times, t$_p$, of the optical emission and the prompt emission variability timescale. The extracted power-law exponent (1.04$\pm$0.05) is consistent with radiative dissipation of the blast wave. These correlations can serve as predictors of unknown Lorentz factors for GRBs and provide insight into the relativistic nature of the blast wave physics of GRB jets.
E. Sonbas, K. Dhuga, P. Veres, et. al.
Thu, 14 Aug 14
50/54
Comments: submitted to ApJL
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