Cosmological Shocks in Adaptive Mesh Refinement Simulations and the Acceleration of Cosmic Rays

Abstract

We present new results characterizing cosmological shocks within adaptive mesh refinement N-Body/hydrodynamic simulations that are used to predict non-thermal components of large-scale structure. This represents the first study of shocks using adaptive mesh refinement. We propose a modified algorithm for finding shocks from those used on unigrid simulations that reduces the shock frequency of low Mach number shocks by a factor of ~3. We then apply our new technique to a large, (512 Mpc/h)^3, cosmological volume and study the shock Mach number (M) distribution as a function of pre-shock temperature, density, and redshift. Because of the large volume of the simulation, we have superb statistics that results from having thousands of galaxy clusters. We find that the Mach number evolution can be interpreted as a method to visualize large-scale structure formation. Shocks with Mach<5 typically trace mergers and complex flows, while 5<Mach<20 and Mach>20 generally follow accretion onto filaments and galaxy clusters, respectively. By applying results from nonlinear diffusive shock acceleration models using the first-order Fermi process, we calculate the amount of kinetic energy that is converted into cosmic ray protons. The acceleration of cosmic ray protons is large enough that in order to use galaxy clusters as cosmological probes, the dynamic response of the gas to the cosmic rays must be included in future numerical simulations.

15 pages, 14 figures, Accepted to ApJ, minor changes made

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Cited by in corpus (11)

• Shock Waves in Eulerian Cosmological Simulations: Main Properties and Acceleration of Cosmic Rays
• A new double radio relic in PSZ1 G096.89+24.17 and a radio relic mass-luminosity relation
• Mass Accretion and its Effects on the Self-Similarity of Gas Profiles in the Outskirts of Galaxy Clusters
• Origin of Cosmic Rays
• Shock finding on a moving-mesh: I. Shock statistics in non-radiative cosmological simulations
• Gamma Rays from Clusters and Groups of Galaxies: Cosmic Rays versus Dark Matter
• Cosmic Ray Origins: An Introduction
• The first Murchison Widefield Array low frequency radio observations of cluster scale non-thermal emission: the case of Abell 3667
• Galaxy Clusters as Reservoirs of Heavy Dark Matter and High-Energy Cosmic Rays: Constraints from Neutrino Observations
• How Much Can We Learn From A Merging Cold Front Cluster? : Insights From X-ray Temperature and Radio Maps of Abell 3667
• Detecting Magnetic Fields in Large-Scale Structure with Radio Polarization