Relativistic MHD simulations of collision-induced magnetic dissipation in Poynting-flux-dominated jets/outflows

TL;DR

This study uses 3D relativistic MHD simulations to show that collisions in Poynting-flux-dominated jets cause significant magnetic energy dissipation through reconnection, supporting models of astrophysical jet emissions.

Contribution

It demonstrates that magnetic reconnection during blob collisions efficiently dissipates electromagnetic energy, with results robust across various parameters and resolutions.

Findings

Approximately 35% electromagnetic energy dissipation efficiency.

Reconnection outflows can form relativistic mini-jets.

Linear relationship between pre- and post-dissipation sigma values.

Abstract

We perform 3D relativistic ideal MHD simulations to study the collisions between high-$\sigma$ (Poynting-flux-dominated) blobs which contain both poloidal and toroidal magnetic field components. This is meant to mimic the interactions inside a highly variable Poynting-flux-dominated jet. We discover a significant electromagnetic field (EMF) energy dissipation with an Alfv\'enic rate with the efficiency around 35\%. Detailed analyses show that this dissipation is mostly facilitated by the collision-induced magnetic reconnection. Additional resolution and parameter studies show a robust result that the relative EMF energy dissipation efficiency is nearly independent of the numerical resolution or most physical parameters in the relevant parameter range. The reconnection outflows in our simulation can potentially form the multi-orientation relativistic mini-jets as needed for several analytical models. We also find a linear relationship between the $\sigma$ values before and after the major EMF energy dissipation process. Our results give support to the proposed astrophysical models that invoke significant magnetic energy dissipation in Poynting-flux-dominated jets, such as the internal collision-induced magnetic reconnection and turbulence (ICMART) model for GRBs, and reconnection triggered mini-jets model for AGNs.