Interaction between Internal Shocks and the Reverse Shock for a GRB in a Dense Stellar Wind

In the most popular scenario for GRBs a relativistic shell is produced by a compact central source (collapsar, BH + WD, BH + NS or NS + NS merger) with a highly non uniform distribution of the Lorentz factor. Internal shocks in the shell are then responsible for the gamma-ray emission. When the shell is decelerated by the surrounding medium a forward (external) shock is formed which accounts for the afterglow observed at lower energy from X-ray to radio frequencies. A reverse shock is also produced and propagates throughout the shell. In most studies, the internal and reverse shocks have been considered separately. However, in the case of a dense wind environment the internal and reverse shocks can be simultaneously present in the shell. We give examples of such situations and show that the burst profiles can be greatly affected. We obtain constraints on the burst parameters to maintain reasonably good profiles for GRBs in dense stellar winds.

Authors and Affiliations

1. Max Planck Institut für Astrophysik, Garching, Germany

   Frédéric Daigne

2. Institut d’Astrophysique de Paris, Paris, France

   Robert Mochkovitch

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