A Search for GeV-TeV Emission from GRBs Using the Milagro Detector

The Milagro detector surveyed the sky almost continuously in the very high energy regime from January 2000 through March 2008. During that time, over 130 GRBs have been detected and well localized by satellites within its 2 sr field of view. We have used Milagro data to search for >1 GeV emission from these bursts. Milagro is a water Cerenkov detector designed primarily for observations in the 0.1-100 TeV energy range. Milagro was operated simultaneously in both standard mode and 'scaler' mode. In the standard analysis, the direction and energy of an incoming particle is determined by reconstructing the air shower produced when the particle interacts in the Earth's atmosphere. In 'scaler' mode, the rates of the PMTs are monitored and fluctuations temporally coincident with GRBs are searched for. No significant emission was discovered using either method and the upper limit on the emission for each burst with known redshift is reported.