Some AGN present jets of matter accelerated at relativistic energies. High energy photons are produced by synchrotron radiation by electrons. Protons should be accelerated as well, and neutrino emission from the jets should result from the decay of pions produced in p-gamma interactions. We are looking for neutrinos from AGN to confirm such scenario. The most powerful explosions detected in the sky, their origin is still unclear.
Current models explain GRBs as a relativistically expanding fireball produced in an explosion.
What can produce such explosions is still unknown, but the expanding matter is shock-accelerated and electromagntic radiation and neutrinos are supposed to be produced by similar physical processes as in the AGN case. There they can annihilate producing neutrinos as a result. The magnetic monopoles of interest for neutrino telescopes are those predicted in Grand Unified theories. Cherenkov emission for a monopole is enhanced by a factor of 3800 in water or ice with respect to a particle with a single charge. The passage of a monopole through a Cherenkov detector will therefore produce a high multiplicity event.