Fermi Gamma-ray Space Telescope

How Fermi revolutionized our physical understanding of GRB prompt emission?

Bing Zhang


For years, the fireball internal shock model has been the leading model to interpret GRB prompt emission. The launch of Fermi greatly opened up the spectral window to observe GRBs, which suggest that the simplest model cannot interpret the majority of the observations. I will review how the combined GBM and LAT data suggest that magnetic fields and a Poynting flux play an important role in defining the GRB prompt emission mechanism. The data suggest that the GRB jet composition is diverse among bursts. For a great fraction of bursts, the emission region is far from the central engine, which is beyond the photosphere and internal shock radii. Synchrotron radiation of electrons from an optically-thin magnetic dissipation region is responsible for the observed prompt GRB emission.