Cosmic Fireworks
Tsvi Piran, Hebrew University
Among the most interesting fireworks observed on the sky are the brightest - gamma ray bursts, GRBs, the least known - neutron star mergers, and the recently puzzling tidal disruption events. I present new results on GRBs progenitors, demonstrating on one hand the existence of a new group of objects: low-luminosity GRBs and providing on the other hand the first direct observational evidence for the Collapsar mechanism. I predict the existence of long lasting flares from merger events. These could help identify gravitational radiation emission from mergers events, increasing the effective sensitivity of gravitational radiation detectors by a large factors. I examine the puzzling Swift events: J1644 and J2058 and explain why they were observed in non-thermal X-ray and not in the expected thermal UV. I also demonstrate surprising (theoretical) links between these three unrelated objects