Speaker
Description
Ever since the early years in the Swift mission, it has been clear that the low-end of the gamma-ray burst (GRB) luminosity distribution has yet to be unveiled, holding the key to the intrinsic rate of GRBs and possibly to their jet structure. Yet, some of the trickiest riddles that GRB astronomy posed to us in the last few years came at the opposite end of the luminosity distribution, where the outrageously bright GRB 221009A shattered the statistics based on several decades of previous GRB observations. Even letting aside the statistics, many properties of this GRB and of its afterglow still lack a convincing explanation. Among these, a bright, narrow spectral frature at around 10 MeV, discovered in Fermi/GBM data around 300 s after the initial precursor, has yet to be fully explained.
In this talk, I will present a scenario that is capable to explain this feature and the apparent temporal evolution of its properties. At the same time, the model explains some puzzling aspects of the TeV afterglow and sheds light on some properties of the progenitor collapsing star.
