Simulation of Relativistic Jets and Associated Self-consistent Radiation

TL;DR

This paper uses simulations to study how relativistic electron-positron jets interact with plasma, generating magnetic fields and radiation relevant to gamma-ray bursts and astrophysical jets.

Contribution

It presents a self-consistent simulation of relativistic jet interactions, magnetic field generation, and radiation emission mechanisms in unmagnetized plasma.

Findings

Electron density increases by a factor of 3.5 at the shock.

Strong electromagnetic fields are generated and contribute to electron deflection.

Magnetic field pile-up may lead to reconnection and particle acceleration.

Abstract

lasma instabilities excited in collisionless shocks are responsible for particle acceleration. We have investigated the particle acceleration and shock structure associated with an unmagnetized relativistic electron-positron jet propagating into an unmagnetized electron-positron plasma. Cold jet electrons are thermalized and slowed while the ambient electrons are swept up to create a partially developed hydrodynamic-like shock structure. In the leading shock, electron density increases by a factor of about 3.5 in the simulation frame. Strong electromagnetic fields are generated in the trailing shock and provide an emission site. These magnetic fields contribute to the electron's transverse deflection behind the shock. Our initial results of a jet-ambient interaction with anti-parallel magnetic fields show pile-up of magnetic fields at the colliding shock, which may lead to reconnection and associated particle acceleration. We will investigate the radiation in transient stage as a possible generation mechanism of precursors of prompt emission. In our simulations we calculate the radiation from electrons in the shock region. The detailed properties of this radiation are important for understanding the complex time evolution and spectral structure in gamma-ray bursts, relativistic jets, and supernova remnants.