Sub-photospheric, radiation mediated shocks in GRBs: Multiple shock emission and the Band spectrum

Abstract

We compute the time integrated, thermal emission produced by a series of radiation mediated shocks that emerge from the photosphere of a GRB outflow. We show that for a sufficiently broad distribution of shock strengths, the overall shape of the time integrated spectral energy distribution below the peak is a power law, $\nu E_{\nu }\propto {\nu }^{\alpha }$, with a slope $1<\alpha <2$. A substructure in the SED can also be produced in this model for certain choices of the shock train distribution. In particular, we demonstrate that our model can reproduce the double-peak SED observed in some bursts, in events whereby a strong shock is followed by a sequence sufficiently weaker ones.

15 pages, 7 figures

References in corpus (3)

• Quasi-blackbody component and radiative efficiency of the prompt emission of gamma-ray bursts
• Very high efficiency photospheric emission in long duration gamma-ray bursts
• Relativistic Radiation Mediated Shocks

Cited by in corpus (7)

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• Gamma-ray burst spectra and spectral correlations from sub-photospheric Comptonization
• The $E_{\mathrm{p}}$ - $E_{\mathrm{iso}}$ relation and the internal shock model
• Observational characteristics of radiation-mediated shocks in photospheric gamma-ray burst emission
• Extreme luminosities in ejecta produced by intermittent outflows around rotating black holes
• Radiation-mediated shocks in gamma-ray bursts: spectral evolution