Mimica 2006 1D数值模拟伽玛暴内激波的碰撞 2

主要内容:
对于两个shell之间的碰撞， 考虑到辐射效率不能直接把两个shell当作整体，然后利用能量和动量守恒计算产生的内能，而应该是一个积分形式。计算了辐射效率，伽玛暴在6%-10%之间。

类似的还有：Mimica et al. 2005, A&A 441, 103

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文章信息:

astro-ph/0611765 [abs, ps, pdf, other] :

Title: Internal shocks in relativistic outflows: collisions of magnetized shells
Authors: Petar Mimica (1), Miguel-Angel Aloy (1, 2), Ewald Mueller (2) ((1) Departamento de Astronomia y Astrofisica, Universidad de Valencia, (2) MPA Garching)
Comments: 17 pages, 18 figures. 2 new references have been added. Accepted for publication in Astronomy and Astrophysics

(Abridged): We study the collision of magnetized irregularities (shells) in relativistic outflows in order to explain the origin of the generic phenomenology observed in the non-thermal emission of both blazars and gamma-ray bursts. We focus on the influence of the magnetic field on the collision dynamics, and we further investigate how the properties of the observed radiation depend on the strength of the initial magnetic field and on the initial internal energy density of the flow. The collisions of magnetized shells and the radiation resulting from these collisions are calculated using the 1D relativistic magnetohydrodynamics code MRGENESIS. The interaction of the shells with the external medium prior to their collision is also determined using an exact solver for the corresponding 1D relativistic magnetohydrodynamic Riemann problem. Our simulations show that two magnetization parameters - the ratio of magnetic energy density and thermal energy density, \alpha_B, and the ratio of magnetic energy density and mass-energy density, \sigma - play an important role in the pre-collision phase, while the dynamics of the collision and the properties of the light curves depend mostly on the magnetization parameter \sigma. The interaction of the shells with the external medium changes the flow properties at their edges prior to the collision. For sufficiently dense shells moving at large Lorentz factors (\simgt 25) these properties depend only on the magnetization parameter \sigma. Internal shocks in GRBs may reach maximum efficiencies of conversion of kinetic into thermal energy between 6% and 10%, while in case of blazars, the maximum efficiencies are \sim 2%.