Ponente
Descripción
Gamma-ray bursts (GRBs) of long duration arise from ultra-relativistic jets that appear shortly after the collapse of massive stars. The highly variable prompt emission, lasting only a few minutes, results from internal dissipation within the jet and is followed by an afterglow that can last several days. This afterglow emission, observable at energies ranging from radio to TeV, is primarily generated by synchrotron and synchrotron self-Compton processes. Despite this, identifying a distinct prompt or early spectral component in GeV-TeV energies has been challenging because of the sensitivity constraints in the MeV-GeV range. This presentation will address the GeV-TeV spectral component of GRB 221009A, the brightest of all-time (BOAT) GRB, as observed in the initial 20 minutes. By modeling the GeV data observed simultaneously by Fermi/LAT from the early phase and AGILE in the later phase, with the TeV data from LHAASO, we can put limits on the magnetic fields and electron energies in the relativistic shock. Although prompt and early very high-energy gamma ray (VHE; E>100 GeV) emissions are crucial to understanding the emission mechanism, it remains understudied due to limitations such as the shorter duration of GRBs, delays between distribution of the triggers from the MeV instruments and notifications received by VHE pointing telescopes, and the slew-time of these telescopes. I will also discuss a novel observation strategy for the pointing VHE facilities (MAGIC, CTAO/LST) to capture prompt and early VHE emissions. This new method has been suggested for MAGIC telescopes, which includes rapid follow-up of the Fermi/GBM triggers to scan the sky localization with shorter exposures (subminute timescale) to cover sky localization of about 100 sq. deg.
