Speaker
Description
Gamma-ray bursts (GRBs) drive powerful relativistic shocks into their surrounding medium, accelerating particles and producing radiation across a broad energy range. Recent detections of TeV photons from GRB afterglows by Cherenkov telescopes such as H.E.S.S. and MAGIC have opened a new window on high-energy emission during the afterglow phase. At lower energies, early X-ray observations with Swift X-Ray Telescope (0.3–10 keV) reveal complex temporal structures — including steep decays, flares, and plateaus — that challenge the standard forward-shock model and point to richer afterglow physics.
We present a systematic multiwavelength analysis of GRB afterglows from 0.3 keV to 100 GeV using data from Swift/XRT, Swift/BAT, and Fermi Large Area Telescope. Our sample includes GRBs with significant high-energy gamma-ray emission. The broadband spectral evolution shows double-peaked spectral energy distributions, which we interpret within a synchrotron self-Compton (SSC) framework. These results constrain the microphysics of the X-ray and GeV emission regions and the properties of the forward shock. The data favor SSC-dominated emission in a wind-like circumburst medium and indicate a notably low magnetic energy fraction. These findings highlight the importance of VHE observations and the capability of the Cherenkov Telescope Array Observatory to probe GRB afterglow microphysics and broadband spectral evolution.
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