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High-energy neutrino emission in gravitational collapses

In this article, we present a study of high-energy neutrino emission in gravitational collapse. A compact star is treated as a complete degenerate Fermi gas of neutrons, protons and electrons. In gravitational collapse, its density reaches the thresholds for muon and pion productions, leading to high-energy neutrinos production. By using adiabatic approximation that macroscopic collapsing processes are much slower than microscopic processes of particle interactions, we adopt equilibrium equations of microscopic processes to obtain the number of neutrino productions. Assuming 10% of variation in gravitational binding energy converted to the energy of produced neutrinos, we obtain fluxes of 10MeV electron-neutrinos and GeV electron and muon neutrinos. In addition, we compute the ratio (< 1) of total muon neutrino number to the total electron neutrino number at the source and at the Earth considering neutrino oscillations. We approximately obtain the number of GeV antineutrino events (\gtrsim 1) in an ordinary detector such as Kamiokande and total energy of neutrino flux (\gtrsim 10^{53} erg), as a function of collapsing star mass.