Hidden source of high-energy neutrinos in collapsing galactic nucleus

We propose a model of a short-lived very powerful source of high energy (HE) neutrinos. It is formed as a result of the dynamical evolution of a galactic nucleus prior to its collapse into a massive black hole and formation of high-luminosity AGN. This stage can be referred to as "pre-AGN". A dense central stellar cluster in the galactic nucleus at the late stage of evolution consists of compact stars (neutron stars and stellar mass black holes). This cluster is sunk deep into the massive gas envelope produced by destructive collisions of a primary stellar population. Frequent collisions of neutron stars in a central stellar cluster are accompanied by the generation of ultrarelativistic fireballs and shock waves. These repeating fireballs result in a formation of the expanding rarefied cavity inside the envelope. The charged particles are effectively accelerated in the cavity and, due to pp collisions in the gas envelope, they produce HE neutrinos. All HE particles, except neutrinos, are absorbed in the thick envelope. The duration of this pre-AGN phase is similar to1 year, the number of the sources can be a few per cosmological horizon. HE neutrino signal can be detected by underground neutrino telescope with effective area S similar to 1 km(2). (C) 2001 Elsevier Science B.V. All rights reserved.