In Search for Extraterrestrial High Energy Neutrinos

In this paper we review the search for astrophysical neutrinos. We begin by summarizing the various theoretical predictions which correlate the expected neutrino flux with data from other messengers, specifically gammas and ultra-high energy cosmic rays. We then review the status and results of neutrino telescopes in operation and decommissioned, the methods used for data analysis and background discrimination. Particular attention is devoted to the challenge enforced by the highly uncertain atmospheric muon and neutrino backgrounds in relation to searches of diffuse neutrino fluxes. Next, we examine the impact of existing limits on neutrino fluxes on studies of the chemical composition of cosmic rays. After that, we show that not only do neutrinos have the potential to discover astrophysical sources, but the huge statistics of atmospheric muons can be a powerful tool as well. We end by discussing the prospects for indirect detection of dark matter with neutrino telescopes.