The radiative processes responsible for the GRBs and their afterglows

Dimitrios Giannios (Purdue ) - March 17, 2014 at 12:10 pm

The radiative mechanisms behind the gamma-ray-burst (GRB) emission remain hotly debated. For quite some time, synchrotron emission from ultra-relativistic electrons has been considered as a promising model for the prompt GRB. Despite intensive study, the serious problems of the model remain. They include the lack of explanation for the observed clustering of the peak of the spectrum at ~1MeV, the sharpness of the peak and the spectral slope below the peak. I will describe, instead, how the radiation from the photosphere of the jet not only accounts for the observed peak energy but also for the overall GRB spectrum if one allows for energy to be injected to electrons around the location of the Thomson photosphere. The resulting spectrum is shaped by Compton scattering rather independently of the details of the dissipation process and the jet composition. At the last part of the talk, I focus on the GRB afterglows and discuss how we can use radio afterglow observations years after the burst to study particle acceleration at subrelativistic shocks.

The seminar will be held in B-1 Hearst Field Annex.


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