  The afterglow emission from gamma-ray bursts (GRBs) is a valuable source of
information to understand the physics of these energetic explosions. The blast
wave model has become the standard to describe the evolution of the afterglow
emission over time and frequency. Thanks to recent developments in the theory
of afterglows and numerical simulations of relativistic outflows, we are able
to model the afterglow emission with realistic dynamics and radiative
processes. Although the models agree with observations remarkably well, the
afterglow emission still contains additional physics, instrumental systematics,
and propagation effects which make the modelling of these events challenging.
In this work, we present a new approach to modelling GRB afterglows, using
Gaussian processes (GPs) to take into account systematics in the afterglow
data. We show that, using this new approach, it is possible to obtain more
reliable estimates of the explosion and microphysical parameters of GRBs. We
present fit results for 5 long GRBs and find a preliminary correlation between
the isotropic energetics and opening angles of GRBs, which confirms the idea of
a common energy reservoir for the kinetic energy of long GRBs.
