Fast Magnetic Reconnection Structures in Poynting Flux-dominated Jets

Abstract

Abstract The ubiquitous relativistic jet phenomena associated with black holes play a major role in high and very-high-energy (VHE) astrophysics. In particular, observations have demonstrated that blazars show VHE emission with time variability from days to minutes (in the gigaelectronvolt and teraelectronvolt bands), implying very compact emission regions. The real mechanism of the particle acceleration process responsible for this emission is still being debated, but magnetic reconnection has lately been discussed as a strong potential candidate. In this work, we present the results of three-dimensional special relativistic magnetohydrodynamic simulations of the development of reconnection events driven by turbulence induced by current-driven kink instability along a relativistic jet. We have performed a systematic identification of all reconnection regions in the system, characterizing their local magnetic field topology and quantifying the reconnection rates. We obtained average rates of 0.051 ± 0.026 (in units of Alfvén speed), which are comparable to the predictions of the theory of turbulence-induced fast reconnection. A detailed statistical analysis also demonstrated that the fast reconnection events follow a log-normal distribution, which is a signature of its turbulent origin. To probe the robustness of our method, we have applied our results to the blazar Mrk 421. Building a synthetic light curve from the integrated magnetic reconnection power, we evaluated the time variability from a power spectral density analysis, obtaining good agreement with observations in the gigaelectronvolt band. This suggests that turbulent fast magnetic reconnection can be a possible process behind the high-energy emission variability phenomena observed in blazars.