Cosmological shock waves

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.

24 pages, 9 figures, accepted for publication in Space Science Reviews, special issue "Clusters of galaxies: beyond the thermal view", Editor J.S. Kaastra, Chapter 7; work done by an international team at the International Space Science Institute (ISSI), Bern, organised by J.S. Kaastra, A.M. Bykov, S. Schindler & J.A.M. Bleeker

References in corpus (12)

• Shocks and cold fronts in galaxy clusters
• Observations of extended radio emission in clusters
• A Physical Relationship Between Electron-Proton Temperature Equilibration and Mach Number in Fast Collisionless Shocks
• Giant Ringlike Radio Structures Around Galaxy Cluster Abell 3376
• Cosmological Shock Waves in the Large Scale Structure of the Universe: Non-gravitational Effects
• Nonlinear Diffusive Shock Acceleration with Magnetic Field Amplification
• Simulation techniques for cosmological simulations
• Thermal radiation processes
• FUV and X-ray absorption in the Warm-Hot Intergalactic Medium
• Equilibration processes in the Warm-Hot Intergalactic Medium
• Thermodynamical properties of the ICM from hydrodynamical simulations
• Soft X-ray and extreme ultraviolet excess emission from clusters of galaxies

Cited by in corpus (8)

• Observations of extended radio emission in clusters
• Measuring the cosmic ray acceleration efficiency of a supernova remnant
• Non-thermal processes in cosmological simulations
• Particle acceleration mechanisms
• Equilibration processes in the Warm-Hot Intergalactic Medium
• Thermodynamical properties of the ICM from hydrodynamical simulations
• Numerical simulations of the Warm-Hot Intergalactic Medium
• Clusters of galaxies: setting the stage