Abstract
Recent observations of very-high-energy (VHE, ≳ 100 GeV) afterglow emission from a few
gamma-ray bursts (GRBs) raised important questions regarding the emission mechanism responsible
for this radiation. So far, synchrotron-self-Compton (SSC) has been primarily used to model
VHE emission from GRBs. As a first approach we have applied NAIMA, a publicly available
code for radiation modelling from relativistic electrons, to model GRB afterglow emission. We
present predictions of multiwavelength energy spectra for GRB 190829A, assuming the emission
is SSC in a wind scenario. In our prior work, using a code developed by us, the SSC model
gave a satisfactory fit to the VHE data for a given set of fixed model parameters for this particular
GRB, with a wind environment preferred over a constant density inter-stellar medium. NAIMA
already includes optimisation tools to perform Markov Chain Monte Carlo (MCMC) fitting of
radiative models to multiwavelength spectra. This is our motivation for this study of comparing
optimised model parameters from NAIMA to those from our own code. Finding a more robust
fit of the model to the observations has implications on future observations, especially by the
CTA Observatory, implying better constraints on the GRB environment and the particle energy
requirements for the emission observed at late times.