Exploring GRB Afterglows in the TeV Era: New Diagnostics of Particle Acceleration

TL;DR

This work tackles how GRB afterglows accelerate particles to extreme energies by leveraging TeV emission and a global, broadband modeling approach. By applying an optimized relativistic fireball framework to TeV-detected GRBs and incorporating synchrotron self-Compton processes, it analyzes the joint temporal and spectral evolution from TeV to X-ray bands. The results reveal a diversity among TeV afterglows, including possible late-time light-curve steepening consistent with jet breaks or spectral effects, and emphasize the diagnostic value of late-time X-ray and GeV-TeV data; AGILE observations lend support to the interpretation. The findings underscore the need for systematic early and long-term TeV follow-up with next-generation Cherenkov telescopes to constrain particle-acceleration physics in GRBs.

Abstract

The TeV gamma-ray band is essential for probing the most extreme particle acceleration processes in the Universe. The recent detections of gamma-ray bursts (GRBs) at these energies offer an incredible opportunity to investigate the origins of such transient events in an unprecedented way. In this presentation, we analyze the afterglows of these GRBs by modeling their synchrotron and inverse Compton emission within an optimized relativistic fireball framework. By comparing observational data with theoretical predictions, we constrain key model parameters and track their temporal evolution. The comparison of different TeV-detected GRBs reveals an intriguing variety among them, potentially reflecting differences in the particle acceleration processes that have to be very fast and able to accelerate to large energies. We discuss how late-time afterglow observations of X-ray and GeV-TeV emissions are crucial for providing diagnostics into the physics of GRBs. At this scope, we also present the most updated results of the AGILE telescope, which support our interpretation. Finally, we highlight theoretical predictions for future TeV observations and their implications for understanding these extreme cosmic explosions.