Observational Evidence of Particles Acceleration by Relativistic Magnetic Reconnection in Gamma-ray Bursts

TL;DR

This paper provides observational evidence that relativistic magnetic reconnection accelerates particles in gamma-ray bursts, revealing new insights into their spectral evolution and potential diagnostics for astrophysical particle acceleration.

Contribution

It is the first to identify signatures of particle acceleration by relativistic magnetic reconnection in GRB spectra through detailed pulse analysis.

Findings

Evidence of spectral break evolution ($E_{p}$ and $E_{cut}$) indicating magnetic reconnection.

Relation between spectral index and flux due to adiabatic cooling.

Anticorrelation between $E_{cut}$ and $L_{iso}$ suggesting new diagnostic methods.

Abstract

Gamma-ray bursts (GRBs) as the most energetic explosions in the modern universe have been studied over half a century, but the physics of the particle acceleration and radiation responsible for their observed spectral behaviors are still not well understood. Based on the comprehensive analysis of the pulse properties in both bright GRB~160625B and GRB~160509A, for the first time, we identify evidences of particle acceleration by relativistic magnetic reconnection from the evolutionary behavior of the two spectral breaks ($E_{\rm p}$ and $E_{\rm cut}$). Meanwhile, the adiabatic cooling process of the emitting particles in the magnetic reconnection regions produces a relation between the spectral index and the flux. We also discuss the physics behind spectral energy correlations. Finally, we argue that the identification of an anticorrelation between $E_{\rm cut}$ and $L_{\rm iso}$ may opens a new avenue for diagnostics of the physics of the particle acceleration and radiation in a variety of astrophysical sources.