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 emision 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. Weak interactions provide the right annihilation cross section for the WIMPs to decouple in the early universe and produce a relic density within the required range to contribute substantially to the energy density of the Universe today. This is essentially what is needed to explain the dark matter problem. In the scattering the neutralino might lose enough energy so as to fall below the escape velocity and become gravitationally trapped. Additional energy losses in a similar fashion will make the trapped neutralinos accumulate around the core of the Earth.