Neutrino Emission from Star-like Sources

Abstract

IN a previous communication¹ we reported some evaluations of the neutrino energy density in the universe taking into account the e⁺ + e⁻→ ν + ν̄ process in the pre-supernova stage of the stars. We found that this energy density may be higher than the energy density of the matter. Here we present a similar evaluation on the basis of the Mannino² hypothesis regarding the star-like objects. It is known that the optical power of these objects is about 10⁴⁶–10⁴⁸ ergs/sec (ref. 3). According to Mannino², this may be due to supernova explosions of as many as 4,000 a year. During the exploding stage the temperature of the stars goes up to 10⁹–10¹⁰° K and the star begins to emit neutrino antineutrino pairs through annihilation of electron-positron pairs which at this high temperature are in equilibrium with the photons. The neutrino emission is of the same order and even higher of the photon emission⁴. Thus we can safely assume that the star-like sources emit 10⁴⁸ ergs/sec as neutrino power. Because the energies of these neutrinos are of the order of a MeV, we have an emission of ∼10⁵⁴ ν/sec/star-like source. (We can obtain these figures also supposing that each supernova inside the star-like object emits ∼10⁴⁵ ergs/sec as neutrino power; since we have 10⁻⁴ supernovse/sec, and since the process goes on for about 200 days², this is the same as saying that at each time we have 10⁻⁴.10⁷ = 10³ supernova in the whole star-like, which means an emission of 10⁴⁵.10³ = 10⁴⁸ ergs/sec from the star-like sources.)