2022/01/31 by Ryota Goto, Katsuaki Asano, Goto, Ryota +1
Physics and Astronomy · #Astro and Planetary Science #FOS: Physical sciences #Gamma-ray bursts and supernovae #High Energy Astrophysical Phenomena (astro-ph.HE) #Solar and Space Plasma Dynamics
paper · pdf · doi:10.48550/arxiv.2201.13028
openalex publication_date 2022/01/31 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
The typical spectrum of the prompt emission of gamma-ray bursts (GRBs) indicates that the electron cooling is suppressed in spite of the strong magnetic field in the standard synchrotron model. Recent Particle-in-Cell simulations show that the particle acceleration by magnetic reconnection in a magnetically dominated plasma can lead to small pitch angles especially in low-energy region. Such a small pitch angle prevents electrons from cooling via synchrotron radiation. In this paper, taking into account the effects of the synchrotron cooling and the adiabatic cooling, we numerically calculate the synchrotron spectra with anisotropic electron distributions. If we require a Poynting flux larger than 1050~erg~s-1 as the model is motivated by magnetic reconnection, the bulk Lorentz factor of ∼ 1000 and the electron minimum Lorentz factor of γ\rm min∼ 104 are required to reproduce the typical GRB spectrum.