Long Term Evolution of Magnetic Turbulence in Relativistic Collisionless Shocks: Electron-Positron Plasmas

Abstract

We study the long term evolution of magnetic fields generated by a collisionless relativistic $e^{+}{e}^{-}$ shock which is initially unmagnetized. Our 2D particle-in-cell numerical simulations show that downstream of such a Weibel-mediated shock, particle distributions are close to isotropic, relativistic Maxwellians, and the magnetic turbulence is highly intermittent spatially, with the non-propagating magnetic fields forming relatively isolated regions with transverse dimension $\sim 10-20$ skin depths. These structures decay in amplitude, with little sign of downstream merging. The fields start with magnetic energy density $\sim (0.1-0.2)$ of the upstream kinetic energy within the shock transition, but rapid downstream decay drives the fields to much smaller values, below $10^{-3}$ of equipartition after $10^3$ skin depths. In an attempt to construct a theory that follows field decay to these smaller values, we explore the hypothesis that the observed damping is a variant of Landau damping in an unmagnetized plasma. The model is based on the small value of the downstream magnetic energy density, which suggests that particle orbits are only weakly perturbed from straight line motion, if the turbulence is homogeneous. Using linear kinetic theory applied to electromagnetic fields in an isotropic, relativistic Maxwellian plasma, we find a simple analytic form for the damping rates, ${\gamma }_k$, in two and three dimensions for small amplitude, subluminous electromagnetic fields. We find that magnetic energy does damp due to phase mixing of current carrying particles as $({\omega }_{p}t{)}^{-q}$ with $q\sim 1$. (abridged)

arXiv comment10 pages, 6 figures, accepted to ApJ; Downsampled version for arXiv. Full resolution figures available at http://astro.berkeley.edu/~pchang/full_res_weibel.pdf

References in corpus (19)

• The Physics of Gamma-Ray Bursts
• Gamma-Ray Bursts and the Fireball Model
• Generation of Magnetic Fields in the Relativistic Shock of Gamma-Ray-Burst Sources
• Interpenetrating plasma shells: near-equipartition magnetic field generation and non-thermal particle acceleration
• Gamma-Ray Burst Afterglow: Polarization and Analytic Light Curves
• Magnetic Field Generation in Collisionless Shocks; Pattern Growth and Transport
• Particle Acceleration in Relativistic Jets due to Weibel Instability
• Long-time evolution of magnetic fields in relativistic GRB shocks
• GRB Phenomenology, Shock Dynamo, and the First Magnetic Fields
• Particle Acceleration and Magnetic Field Generation in Electron-Positron Relativistic Shocks
• Saturation mechanism of the Weibel instability in weakly magnetized plasmas
• Synchrotron emission in small scale magnetic field as possible explanation for prompt emission spectra of gamma-ray bursts
• Gamma-Ray Burst Afterglow emission with a decaying magnetic field
• The Cosmic Ray Precursor of Relativistic Collisionless Shocks: A Missing Link in Gamma-Ray Burst Afterglows
• Magnetic Fields in Gamma-Ray Bursts: A Short Review
• Weibel Filament Decay and Thermalization in Collisionless Shocks and Gamma-Ray Burst Afterglows
• Steady-State Electrostatic Layers from Weibel Instability in Relativistic Collisionless Shocks
• Self-Similar Collisionless Shocks
• Magnetic field generation by the Weibel instability at temperature gradients in collisionless plasmas

Cited by in corpus (117)

• The Physics of Gamma-Ray Bursts and Relativistic Jets
• Particle acceleration in relativistic collisionless shocks: Fermi process at last?
• The physics of galactic winds driven by active galactic nuclei
• Particle Acceleration in Relativistic Magnetized Collisionless Electron-Ion Shocks
• The Maximum Energy of Accelerated Particles in Relativistic Collisionless Shocks
• The Binary Neutron Star event LIGO/VIRGO GW170817 a hundred and sixty days after merger: synchrotron emission across the electromagnetic spectrum
• Particle Acceleration in Relativistic Magnetized Collisionless Pair Shocks: Dependence of Shock Acceleration on Magnetic Obliquity
• The microphysics of collisionless shock waves
• The Cosmological Impact of Luminous TeV Blazars I: Implications of Plasma Instabilities for the Intergalactic Magnetic Field and Extragalactic Gamma-Ray Background
• Relativistic Shocks: Particle Acceleration and Magnetization
• Magnetic Fields In Relativistic Collisionless Shocks
• Non-relativistic Collisionless Shocks in Unmagnetized Electron-Ion Plasmas
• Weibel, Two-Stream, Filamentation, Oblique, Bell, Buneman... which one grows faster ?
• Magnetic field evolution in relativistic unmagnetized collisionless shocks
• On electromagnetic instabilities at ultra-relativistic shock waves
• Synthetic Spectra from PIC Simulations of Relativistic Collisionless Shocks
• Weibel instability and associated strong fields in a fully 3D simulation of a relativistic shock
• A new approach to simulating collisionless dark matter fluids
• The Role of Stochastic Acceleration in the Prompt Emission of Gamma-Ray Bursts: Application to Hadronic Injection
• Three-Dimensional Simulations of MHD Turbulence Behind Relativistic Shock Waves and Their Implications for GRBs
• A Particle Module for the PLUTO Code: I - an implementation of the MHD-PIC equations
• Slow Heating Model of Gamma-Ray Burst: Photon Spectrum and Delayed Emission
• Signatures of a Maxwellian Component in Shock-Accelerated Electrons in GRBs
• Synchrotron signature of a relativistic blast wave with decaying microturbulence
• Gamma-ray burst afterglows from trans-relativistic blast wave simulations
• Nonrelativistic collisionless shocks in weakly magnetized electron--ion plasmas: two-dimensional particle-in-cell simulation of perpendicular shock
• Low-energy Spectra of Gamma-ray Bursts from Cooling Electrons
• On the magnetization of gamma-ray burst blast waves
• Unstable GRB photospheres and electron-positron annihilation lines
• On Fermi acceleration and MHD-instabilities at ultra-relativistic magnetized shock waves
• Constraining the magnetic field structure in collisionless relativistic shocks with a radio afterglow polarization upper limit in GW170817
• Perpendicular relativistic shocks in magnetized pair plasma
• 3D modeling of collisionless shocks
• Experimental observation of a current-driven instability in a neutral electron-positron beam
• From primordial seed magnetic fields to the galactic dynamo
• On the origin of >10 GeV photons in gamma-ray burst afterglows
• Collisionless Weibel shocks: full formation mechanism and timing
• Persistence of precursor waves in two-dimensional relativistic shocks
• Multi-wavelength view of the close-by GRB 190829A sheds light on gamma-ray burst physics
• PIC methods in astrophysics: Simulations of relativistic jets and kinetic physics in astrophysical systems
• Particle transport and heating in the microturbulent precursor of relativistic shocks
• How large can the electron to proton mass ratio be in Particle-In-Cell simulations of unstable systems?
• Gamma-Ray Burst Spectrum with Decaying Magnetic Field
• PIC Simulation Methods for Cosmic Radiation and Plasma Instabilities
• Towards understanding the physics of collisionless relativistic shocks
• Time-dependent particle acceleration in supernova remnants in different environments
• Nonrelativistic parallel shocks in unmagnetized and weakly magnetized plasmas
• Precursor Wave Emission Enhanced by Weibel Instability in Relativistic Shocks
• Magnetic Field Generation in Core-Sheath Jets via the Kinetic Kelvin-Helmholtz Instability
• A relativistic partially electromagnetic planar plasma shock
• Particle acceleration, magnetization and radiation in relativistic shocks
• Physics and phenomenology of weakly magnetized, relativistic astrophysical shock waves
• Non-linear collisionless damping of Weibel turbulence in relativistic blast waves
• Radiative cooling in relativistic collisionless shocks. Can simulations and experiments probe relevant GRB physics?
• Long-term Evolution of Relativistic Unmagnetized Collisionless Shocks
• Evolution and observational signatures of the cosmic ray electron spectrum in SN 1006
• Shock formation in electron-ion plasmas: mechanism and timing
• Simulation study of the formation of a non-relativistic pair shock
• Long wavelength unstable modes in the far upstream of relativistic collisionless shocks
• Physics of relativistic collisionless shocks: III The suprathermal particles
• A Narrow Uniform Core with a Wide Structured Wing: Modeling the TeV and Multi-wavelength Afterglows of GRB 221009A
• Electron-positron annihilation into two photons in an intense plane-wave field
• Acceleration in perpendicular relativistic shocks for plasmas consisting of leptons and hadrons
• Weibel-Mediated Shocks Propagating into Inhomogeneous Electron-Positron Plasmas
• The Status and future of ground-based TeV gamma-ray astronomy. A White Paper prepared for the Division of Astrophysics of the American Physical Society
• The synchrotron-self-Compton spectrum of relativistic blast waves at large Y
• Structure of a collisionless pair jet in a magnetized electron-proton plasma: flow-aligned magnetic field
• A Novel Emission Spectrum From A Relativistic Electron Moving In A Random Magnetic Field
• Shock Vorticity Generation from Accelerated Ion Streaming in the Precursor of Ultrarelativistic Gamma-Ray Burst External Shocks
• Impact of continuous particle injection on generation and decay of the magnetic field in collisionless shocks
• Dynamo in weakly collisional nonmagnetized plasmas impeded by Landau damping of magnetic fields
• Modeling Spectral Variability of Prompt GRB Emission within the Jitter Radiation Paradigm
• On the prospects of gamma-ray burst detection in the TeV band
• Microphysics of Relativistic Collisionless Electron-ion-positron Shocks
• Particle acceleration and radiation friction effects in the filamentation instability of pair plasmas
• Magnetic field amplification by a plasma cavitation instability in relativistic shock precursors
• Jitter radiation in gamma-ray bursts and their afterglows: emission and self-absorption
• Generating ultra-dense pair beams using 400 GeV/c protons
• Collisional behaviors of astrophysical collisionless plasmas
• Weibel instability driven by spatially anisotropic density structures
• The impact of kinetic effects on the properties of relativistic electron-positron shocks
• Plasma kinetic effects in relativistic radiation mediated shocks
• Particle acceleration at ultrarelativistic, perpendicular shock fronts
• Synchrotron Polarization of Gamma-Ray Burst Afterglow Shocks with Hydrodynamic-scale Turbulent Magnetic Field
• A Study of the Early-stage Evolution of Relativistic Electron-Ion Shock using 3D PIC Simulations
• Saturation of the asymmetric current filamentation instability under conditions relevant to relativistic shock precursors
• The Weibel Instability inside the Electron-Positron Harris Sheet
• Radiative diagnostics for sub-Larmor scale magnetic turbulence
• The maximum energy of shock-accelerated electrons in a microturbulent magnetic field
• Spectral Lag for a Radiating Jet Shell with a High Energy Cut-off Radiation Spectrum
• Radiation from relativistic shocks with turbulent magnetic fields
• Angular Dependence of Jitter Radiation Spectra from Small-Scale Magnetic Turbulence
• Jitter radiation images, spectra, and light curves from a relativistic spherical blastwave
• Simulation of Relativistic Jets and Associated Self-consistent Radiation
• Detailed Analysis of Filamentary Structure in the Weibel Instability
• Gamma-Ray Burst prompt emission from the synchrotron radiation of relativistic electrons in a rapidly decaying magnetic field
• Electron Weibel instability and~quasi-magnetostatic structures in~an~expanding collisionless plasma
• The influence of the mass-ratio on the acceleration of particles by filamentation instabilities
• Multi-scale magnetic field structures in an expanding elongated plasma cloud with hot electrons subject to an external magnetic field
• Diffusive acceleration in relativistic shocks: particle feedback
• Two-dimensional particle simulation of the boundary between a hot pair plasma and magnetized electrons and protons: out-of-plane magnetic field
• Acceleration of cosmic rays in presence of magnetohydrodynamic fluctuations at small scales
• PIC simulation study of the interaction between a relativistically moving leptonic micro-cloud and ambient electrons
• The elusive synchrotron precursor of collisionless shocks
• Collisionless shock in a relativistically hot unmagnetized electron-positron plasma
• Dark plasmas in the nonlinear regime: constraints from particle-in-cell simulations
• Relativistic shock acceleration and some consequences
• Whence particle acceleration
• Long Term Evolution of Magnetic Turbulence in Relativistic Collisionless Shocks
• Radiative signatures of electron-ion shocks in BL Lac type objects
• Fermi acceleration in relativistic collisionless plasma shocks correlates with anisotropic energy gains
• Properties of magnetic turbulence in GRB afterglows
• Plasmas in Gamma-Ray Bursts: particle acceleration, magnetic fields, radiative Processes and environments
• Radiation from relativistic jets
• Three-dimensional structure and stability of discontinuities between unmagnetized pair plasma and magnetized electron-proton plasma
• Macroscopic magnetization of primordial plasma by virial shocks
• Section on Extragalactic Science Topics of the White Paper on the Status and Future of Ground-Based TeV Gamma-Ray Astronomy