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A Revised Limit of the Lorentz Factors of GRBs with Two Emitting Regions
Yuan-Chuan Zou, Yi-Zhong Fan, Tsvi Piran
Fermi observations of GeV emission from GRBs have suggested that the Lorentz factor of some GRBs is around a thousand or even higher. At the same time the same Fermi observations h…
A New Limit on the Distances of Nuclei UHECRs Sources
Tsvi Piran
Recent evidence from the Pierre Auger Observatory suggests a transition, at 5 EeV-10EeV in the composition of Ultra High Energy Cosmic Rays (UHECRs), from protons to heavier nuclei…
Modifications to Lorentz invariant dispersion in relatively boosted frames
Uri Jacob, Flavio Mercati, Giovanni Amelino-Camelia +1
We investigate the implications of energy-dependence of the speed of photons, one of the candidate effects of quantum-gravity theories that has been most studied recently, from the…
On The External Shock Synchrotron Model for GRBs' GeV Emission
Tsvi Piran, Ehud Nakar
The dominant component of the (100 MeV - 50 GeV) GRB emission detected by LAT starts with a delay relative to the prompt soft (sub-MeV) gamma-rays and lasts long after the soft com…