2020ApJ...905..105A -
Astrophys. J., 905, 105-105 (2020/December-3)
Probing particle acceleration through broadband early afterglow emission of MAGIC gamma-ray burst GRB 190114C.
ASANO K., MURASE K. and TOMA K.
Abstract (from CDS):
Major Atmospheric Gamma Imaging Cerenkov Telescopes (MAGIC) detected the gamma-ray afterglow of GRB 190114C, which can constrain microscopic parameters of the shock-heated plasma emitting non-thermal emission. Focusing on the early afterglow of this event, we numerically simulate the spectrum and multi-wavelength light curves with constant and wind-like circumstellar medium using a time-dependent code. Our results show that the electron acceleration timescale at the highest energies is likely shorter than 20 times the gyroperiod to reproduce the GeV gamma-ray flux and its spectral index reported by Fermi. This gives an interesting constraint on the acceleration efficiency for Weibel-mediated shocks. We also constrain the number fraction of non-thermal electrons fe, and the temperature of the thermal electrons. The early optical emission can be explained by the thermal synchrotron emission with fe <= 0.01. On the other hand, the X-ray light curves restrict efficient energy transfer from protons to the thermal electrons, and fe ∼ 1 is required if the energy fraction of the thermal electrons is larger than ∼10%. The parameter constraints obtained in this work give important clues to probing plasma physics with relativistic shocks.
Abstract Copyright:
© 2020. The American Astronomical Society. All rights reserved.
Journal keyword(s):
Gamma-ray bursts - Non-thermal radiation sources - Shocks
Simbad objects:
3
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