Kinetic simulations of mildly relativistic shocks I: particle acceleration in high Mach number shocks

Abstract

We use fully kinetic particle-in-cell simulations with unprecedentedly large transverse box sizes to study particle acceleration in weakly-magnetized mildly relativistic shocks traveling at a velocity $\approx 0.75c$ and a Mach number of 15. We examine both subluminal (quasi-parallel) and superluminal (quasi-perpendicular) magnetic field orientations. We find that quasi-parallel shocks are mediated by a filamentary non-resonant (Bell) instability driven by non-thermal ions, producing magnetic fluctuations on scales comparable to the ion gyro-radius. In quasi-parallel shocks, both electrons and ions are accelerated into non-thermal power-laws whose maximum energy grows linearly with time. The upstream heating of electrons is small, and the two species enter the shock front in rough thermal equilibrium. The shock's structure is complex; the current of reflected non-thermal ions evacuates cavities in the upstream which form filaments of amplified magnetic fields once advected downstream. At late times, $10\%$ of the shock's energy goes into non-thermal protons and $\gtrsim 10\%$ into magnetic fields. We find that properly capturing the magnetic turbulence driven by the non-thermal ions is important for properly measuring the energy fraction of non-thermal electrons, ${\epsilon }_e$. We find ${\epsilon }_e\sim 5\times 10^{-4}$ for quasi-parallel shocks with $v=0.75c$, slightly larger than what was measured in simulations of non-relativistic shocks. In quasi-perpendicular shocks, no non-thermal power-law develops in ions or electrons. The ion acceleration efficiency in quasi-parallel shocks suggests that astrophysical objects that could host mildly relativistic quasi-parallel shocks -- for example, the jets of active galactic nuclei or microquasars -- may be important sources of cosmic rays and their secondaries, such as gamma-rays and neutrinos.

arXiv commentSubmitted to MNRAS. 14 pages, 18 figures

References in corpus (28)

• Generation of Magnetic Fields in the Relativistic Shock of Gamma-Ray-Burst Sources
• Particle acceleration by ultra-relativistic shocks: theory and simulations
• Particle acceleration in relativistic collisionless shocks: Fermi process at last?
• Simulations of Ion Acceleration at Non-relativistic Shocks. I. Acceleration Efficiency
• Analytic Light-Curves of Gamma-Ray Burst Afterglows: Homogeneous versus Wind External Media
• Physical parameters of GRB 970508 and GRB 971214 from their afterglow synchrotron emission
• Particle Acceleration in Relativistic Magnetized Collisionless Electron-Ion Shocks
• The Maximum Energy of Accelerated Particles in Relativistic Collisionless Shocks
• Particle acceleration at ultrarelativistic shocks: an eigenfunction method
• On the structure of relativistic collisionless shocks in electron-ion plasmas
• Particle Acceleration in Relativistic Magnetized Collisionless Pair Shocks: Dependence of Shock Acceleration on Magnetic Obliquity
• Strong evidences of hadron acceleration in Tycho's Supernova Remnant
• Simultaneous Acceleration of Protons and Electrons at Nonrelativistic Quasiparallel Collisionless Shocks
• Simulations of Ion Acceleration at Non-relativistic Shocks. II. Magnetic Field Amplification
• Magnetic Fields In Relativistic Collisionless Shocks
• The spectrum of particles accelerated in relativistic, collisionless shocks
• Diffusive Acceleration of Particles at Oblique, Relativistic, Magnetohydrodynamic Shocks
• Electron Injection by Whistler Waves in Non-relativistic Shocks
• Simulations of Ion Acceleration at Non-relativistic Shocks. III. Particle Diffusion
• Cosmic-ray-induced filamentation instability in collisionless shocks
• A filamentation instability for streaming cosmic-rays
• Electron Accelerations at High Mach Number Shocks: Two-Dimensional Particle-In-Cell Simulations in Various Parameter Regimes
• Monte Carlo Simulations of Nonlinear Particle Acceleration in Parallel Trans-relativistic Shocks
• A current driven instability in parallel, relativistic shocks
• Electron Pre-Acceleration at Nonrelativistic High-Mach-Number Perpendicular Shocks
• Particle Transport in intense small scale magnetic turbulence with a mean field
• Nonrelativistic parallel shocks in unmagnetized and weakly magnetized plasmas
• Particle acceleration at shock waves moving at arbitrary speed: the case of large scale magnetic field and anisotropic scattering

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