2021ApJ...917...95Z -
Astrophys. J., 917, 95-95 (2021/August-3)
Nearby SN-associated GRB 190829A: environment, jet structure, and VHE gamma-ray afterglows.
ZHANG L.-L., REN J., HUANG X.-L., LIANG Y.-F., LIN D.-B. and LIANG E.-W.
Abstract (from CDS):
We present a self-consistent paradigm to interpret the striking features of nearby low-luminosity GRB 190829A. Its prompt gamma-ray lightcurve has two separated pulses. We propose that the interaction of the hard prompt gamma-ray photons (Ep=624–303+2432 keV) of its initial pulse with the dusty medium (AV = 2.33) not only results in the second soft gamma-ray pulse (Ep ∼ 12 keV) but also makes a pre-accelerated e± -rich medium shell via the γγ annihilation. In this paradigm, we show that the observed radio, optical, and X-ray afterglow lightcurves are well-fitted with the forward shock model. Its jet is almost isotropic (θj > 1.0 rad) with a Lorentz factor of ∼35, and the electron density of the e± -rich medium shell is ∼15 cm–3, which is about seven times higher than the electron density of its normal surrounding medium. The GRB ejecta catches up with and propagates into the e± -rich medium shell at a region of R = (4.07-6.46) x 1016 cm. This results in a bright afterglow bump at ∼103 seconds after the GRB trigger. The predicted very high energy (VHE) gamma-ray emission from the synchrotron self-Compton process agrees with the H.E.S.S. observation. The derived broadband spectral energy distribution shows that GRB 190829A like nearby GRBs would be promising targets of the VHE gamma-ray telescopes, such as H.E.S.S., MAGIC, and CTA (Cerenkov Telescope Arrays).
Abstract Copyright:
© 2021. The American Astronomical Society. All rights reserved.
Journal keyword(s):
Gamma-ray bursts
Simbad objects:
21
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