Institute for Advanced Study/Princeton University Joint Astrophysics Colloquium - NOTE 10:45 START TIME!

A classic problem posed by long gamma ray bursts (GRB) is that the energy output requires gravitational energy release so deep within the host star that the prompt gamma rays should, upon naive consideration, have been obscured. It is suggested that photons emitted along the direction of the emitting plasma's motion are indeed geometrically blocked by optically thick baryonic matter, and that we usually see the photons that are emitted nearly backward in the frame of the emitting plasma. Many puzzling observations concerning GRB then fall into place.