http://arxiv.org/abs/1601.03735
We set up a simple model to compute the bolometric light curve and time dependent spectrum of a single pulse of a Gamma-Ray Burst under the assumption that the pulse rise and decay are dominated by the shell curvature effect. For the first time, our model includes the effect of an arbitrary off-axis viewing angle. We show that a pulse observed off-axis is (i) longer, (ii) softer and (iii) displays a different hardness-intensity correlation with respect to the same pulse seen on-axis. For each of these effects, we provide an intuitive physical explanation. We then show how a synthetic light curve made by a superposition of pulses changes with increasing viewing angle. We find that many observed properties found in time-resolved spectral analysis of Gamma-Ray Burst light curves are reproduced in curves with a slightly off-axis viewing angle. Such properties include the fact that the spectral peak energy evolution tracks the variations in flux, leading them slightly. Based on these results, we argue that low luminosity Gamma-Ray Bursts are consistent with being ordinary bursts seen off-axis.
O. Salafia, G. Ghisellini, A. Pescalli, et. al.
Mon, 18 Jan 16
21/50
Comments: 11 pages, 14 figures, submitted to MNRAS main journal
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