Cosmological Shock Waves |
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Authors: | A M Bykov K Dolag F Durret |
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Institution: | (1) A.F. Ioffe Institute of Physics and Technology, St. Petersburg, 194021, Russia;(2) Max-Planck-Institut für Astrophysik, P.O. Box 1317, 85741 Garching, Germany;(3) Institut d’Astrophysique de Paris, CNRS, Université Pierre et Marie Curie, 98bis Bd Arago, 75014 Paris, France |
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Abstract: | 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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Keywords: | Large scale structure of universe Shock waves Acceleration of particles X-rays: galaxies: clusters |
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