TY - JOUR T1 - Magnetohydrodynamics of Gamma-Ray Burst Outflows Y1 - 2001 A1 - Vlahakis, Nektarios A1 - Königl, Arieh KW - Astrophysics KW - Gamma Rays: Bursts KW - ISM: jets and outflows KW - magnetohydrodynamics: MHD KW - methods: analytical KW - relativity AB - Using relativistic, axisymmetric, ideal MHD, we examine the outflow from a disk around a compact object, taking into account the baryonic matter, the electron-positron/photon fluid, and the large-scale electromagnetic field. Focusing on the parameter regime appropriate to γ-ray burst outflows, we demonstrate, through exact self-similar solutions, that the thermal force (which dominates the initial acceleration) and the Lorentz force (which dominates farther out and contributes most of the acceleration) can convert up to ~50% of the initial total energy into asymptotic baryon kinetic energy. We examine how baryon loading and magnetic collimation affect the structure of the flow, including the regime where emission due to internal shocks could take place. VL - 563 SN - 0004-637X UR - https://ui.adsabs.harvard.edu/abs/2001ApJ...563L.129V JO - The Astrophysical Journal ER -