Neutrino pair annihilation (nu {bar{nu }}rightarrow e^-e^+) in the presence of quintessence surrounding a black hole

Abstract

Quintessence fields, introduced to explain the speed-up of the Universe, might affect the geometry of spacetime surrounding black holes, as compared to the standard Schwarzschild and Kerr geometries. In this framework, we study the neutrino pairs annihilation into electron-positron pairs (nu {bar{nu }}rightarrow e^-e^+) near the surface of a neutron star, focusing, in particular, on the Schwarzschild-like geometry in presence of quintessence fields. The effect of the latter is to increase the photon-sphere radius (R_{ph}), increasing in such a way the maximum energy deposition rate near to R_{ph}. The rate turns out to be several orders of magnitude greater than the rate computed in the framework of General Relativity. These results might provide a rising in the GRBs energy emitted from a close binary neutron star system and might be used to constraints the parameters of the quintessence model. Finally we theoretically study the effects of rotation on the neutrino energy deposition.