Giant agn flares and cosmic ray bursts

We predict a new class of very intense, short-duration active galactic nucleus (AGN) flares capable of accelerating the highest energy cosmic rays, resulting from the tidal disruption of a star or from a disk instability. The rate and power of these flares readily explains the observed flux and density statistics of ultrahigh energy cosmic ray. The photon bursts produced by the predicted AGN flares are discussed; they may soon be detectable. Observations are shown to exclude that continuous jets of powerful AGNs are the sole source of ultrahigh energy cosmic rays; the stringent requirements for gamma-ray bursts to be the source are delineated.