Search for the Diffuse Neutrino Flux from Astrophysical Sources

Abstract

High energy neutrinos in the range from 100 GeV up to 107 GeV are expected from a wide class of galactic and extragalactic astrophysical objects. Neutrino production requires the existence of hadronic processes and is generally described in the picture of the so-called beam dump model [1]: high energy protons accelerated in proximity of compact objects by shocks waves or plasma turbulence interact with photons or target matter surrounding the source, producing pions. Neutrinos of electron and muon flavors originate from decay of charged pions, as well as from decay of generated muons. In the same hadronic chains, high energy Υ-rays are expected to be produced through neutral pion decay. Like Υ-rays, neutrinos can travel undeflected through the Universe. Neutrinos however are much less absorbed than photons and thus make a more powerful tool for astronomy searches. Many of the candidate sources of neutrinos (binary systems, supernovae remnants, AGNs, GRBs etc) have already been recognized as gamma rays emitters at energy higher than 100 GeV: this provides an important hint to neutrino astronomy, even if the observed Υ-ray energies are not high enough to exclude the electromagnetic production mechanisms, such as synchrotron or inverse Compton processes. In this scenario, the detection of high energy neutrinos would open a new field of research, complementary to Υ-ray astronomy and essential in order to investigate the inner structure of the most interesting cosmic objects. Further details on this item are given in [2].