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Abstract: Large-scale structure formation, accretion and merging processes, AGNactivity produce cosmological gas shocks. The shocks convert a fraction of theenergy of gravitationally accelerated flows to internal energy of the gas.Being the main gas-heating agent, cosmological shocks could amplify magneticfields and accelerate energetic particles via the multi-fluid plasma relaxationprocesses. We first discuss the basic properties of standard single-fluidshocks. Cosmological plasma shocks are expected to be collisionless. We thenreview the plasma processes responsible for the microscopic structure ofcollisionless shocks. A tiny fraction of the particles crossing the shock isinjected into the non-thermal energetic component that could get a substantialpart of the ram pressure power dissipated at the shock. The energetic particlespenetrate deep into the shock upstream producing an extended shock precursor.Scaling relations for postshock ion temperature and entropy as functions ofshock velocity in strong collisionless multi-fluid shocks are discussed. Weshow that the multi-fluid nature of collisionless shocks results in excessivegas compression, energetic particle acceleration, precursor gas heating,magnetic field amplification and non-thermal emission. Multi-fluid shocksprovide a reduced gas entropy production and could also modify the observablethermodynamic scaling relations for clusters of galaxies.



Autor: A.M. Bykov, K. Dolag, F. Durret

Fuente: https://arxiv.org/







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