Cosmological shock waves

被引:48
|
作者
Bykov, A. M. [1 ]
Dolag, K. [2 ]
Durret, F. [3 ]
机构
[1] AF Ioffe Phys Tech Inst, St Petersburg 194021, Russia
[2] Max Planck Inst Astrophys, D-85741 Garching, Germany
[3] Univ Paris 06, Inst Astrophys Paris, CNRS, F-75014 Paris, France
基金
美国国家航空航天局;
关键词
large scale structure of universe; shock waves; acceleration of particles; X-rays : galaxies : clusters;
D O I
10.1007/s11214-008-9312-9
中图分类号
P1 [天文学];
学科分类号
0704 ;
摘要
Large-scale structure formation, accretion and merging processes, AGN activity produce cosmological gas shocks. The shocks convert a fraction of the energy of gravitationally accelerated flows to internal energy of the gas. Being the main gas-heating agent, cosmological shocks could amplify magnetic fields and accelerate energetic particles via the multi-fluid plasma relaxation processes. We first discuss the basic properties of standard single-fluid shocks. Cosmological plasma shocks are expected to be collisionless. We then review the plasma processes responsible for the microscopic structure of collisionless shocks. A tiny fraction of the particles crossing the shock is injected into the non-thermal energetic component that could get a substantial part of the ram pressure power dissipated at the shock. The energetic particles penetrate deep into the shock upstream producing an extended shock precursor. Scaling relations for postshock ion temperature and entropy as functions of shock velocity in strong collisionless multi-fluid shocks are discussed. We show that the multi-fluid nature of collisionless shocks results in excessive gas compression, energetic particle acceleration, precursor gas heating, magnetic field amplification and non-thermal emission. Multi-fluid shocks provide a reduced gas entropy production and could also modify the observable thermodynamic scaling relations for clusters of galaxies.
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页码:119 / 140
页数:22
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