Neutrino emission by the photo production process in a hyper-accretion disk

Abstract

MacFadyen & Woosley (1999) have studied two models of a hypernova, where a hyper-accreting disk is created in the core of a star. Their code requires an accurate model of local energy loss given by neutrino emission. An emissivity of 3.5×10[superscript 34] ergs cm[superscript -3] s[superscript -1] can be calculated using conservation laws of an accretion disk around a black hole. MacFadyen & Woosley (1999) used 9×10[ superscript 34] ergs cm[superscript -3] s[superscript -1] in their models. In particular, in this thesis, I analyze the contribution of the photo neutrino process to the emissivity. For a temperature of 10[superscript 10] K, a density of 10[superscript 9] g/cm[superscript 3], and a chemical potential of 2.02×10[superscript 7] eV, emissivities of (8.7 +/- 0.1)×10[superscript 21] and (7.0 +/- 0.2)×10[superscript 21] ergs cm[superscript -3] sec[superscript -1] are found. Rates of (8.6 +/- 0.1)×10[superscript 26] and (7.3 +/- 0.2)×10[superscript 26] cm[superscript -3] sec[superscript -1] are also found with average neutrinos energies of (6.2 +/- 0.2) and (6.0. +/- 0.3) MeV. The calculation of the photo neutrino production process is a more robust calculation than seen in previous work with the use of the complete scatting amplitude, and the use of Monte Carlo integration methods.