High Energy Neutrinos and Photons from Gamma-Ray Bursts and Active Galaxies

AST 0098416

Meszaros

Gamma ray bursts (GRBs) and the active nuclei of galaxies (AGNs) outshine every other gamma-ray source in the sky. GRB are stellar remnants thought to be powered by black holes with masses several times the mass of the sun, which, in a few seconds, emit as much energy as our entire Milky Way does in a hundred years. However, it is not understood what kinds of stars give rise to these events, nor what is the exact mechanism whereby they produce gamma-rays, neutrinos and charged cosmic rays, nor how frequently or how far back in time they occur. AGNs, on the other hand, are suspected of harboring giant black holes, more massive than millions of suns, and are known to accelerate jets of electrons, which produce radio waves, light and ultra-high energy gamma rays. However, it is unclear if these jets also contain protons and neutrons, like some giant neutron gun, which would also entail highly penetrating neutrinos. Both ultra-high energy protons and neutrinos are targets for giant cosmic ray and neutrino telescopes being built by NSF in Argentina and in the South Pole, which will probe energies millions of times higher than any ever achieved in Earth laboratories. This is uncharted territory, and we need to know the theoretical ranges of possible results. A comparison of theoretical models with these experiments is imperative, in order to test the validity of current ideas (or the need for new ones) about how our Universe functions. This project will identify key features distinguishing different conceptions, which will allow an optimization of the design of planned experiments, and the testing of the various competing theories. The results would have far-reaching consequences for a range of questions in astrophysics, including how far into the cosmic past can we peer, what is the total energy content of the Universe, and are the laws of physics different or not at these higher energies and earlier times in the age of the Universe Funding for this project was provided by the NSF program for Extragalactic Astronomy & Cosmology (AST/EXC).

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