New Clues to an Old Mystery: GRB Emission Mechanisms and Hidden Populations with Maria Edvige Ravasio

More than 50 years after their discovery, Gamma-Ray Bursts (GRBs) remain among the most puzzling powerful phenomena in the Universe. Recent progress in modeling their prompt emission suggests that the observed spectra can be explained by synchrotron radiation from a non-thermal particle distribution that does not cool completely — severely challenging the GRB standard model.

In this talk, I will present recent discoveries from the study of prompt emission at high energies (keV-GeV), offering new insights into the physics of GRBs' jets (e.g., bulk Lorentz factor, distance from the central engine, particle acceleration). Among others, I will also present the first detection of a transient emission line at MeV energies in the prompt emission spectrum of the brightest GRB ever observed. The identification of this highly-significant (>6 sigma), luminous (~10^50 erg/s), and narrow (width~1 MeV) spectral feature could strongly impact our understanding of the physics of GRBs, offering key insights into the poorly understood jet composition and dissipation processes.

I will conclude by discussing how the recently launched Einstein Probe satellite, designed to detect soft X-ray transients, will give us an unprecedented opportunity to capture GRB jet X-ray emission and reveal previously hidden populations of low-luminosity and high-redshift GRBs.

Sponsored by the McDonnell Center for the Space Sciences.