A model for GRB jets

Author: Vlahakis Nektarios   Königl Arieh  

Publisher: Springer Publishing Company

ISSN: 0004-640X

Source: Astrophysics and Space Science, Vol.287, Iss.1-4, 2003-01, pp. : 249-252

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Abstract

By using relativistic, axisymmetric, ideal MHD, we examine the motion of the baryon/e±/ photon fluid that emanates from a stellar-mass compact object/debris-disk system (a common outcome of many progenitor models). We prove that the motion can be described as a frozen pulse, which permits the study of each shell of the pancake-shaped outflow using steady-state equations. The ejected energy flux is dominated by the electromagnetic (Poynting) contribution, but it can also have a nonnegligible e±/radiation (thermal fireball) component. We demonstrate, through exact self-similar solutions, that the flow is first thermally and subsequently magnetically accelerated up to equipartition between kinetic and Poynting fluxes, i.e., ∼ 50% of the total energy is converted into baryonic kinetic energy. The electromagnetic forces also collimate the flow, reaching a cylindrical structure asymptotically.

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