The production of muon and tau neutrinos in core-collapse supernovae
LE3 .A278 2009
Bachelor of Science
Neutrino interactions with matter composed of neutrons, protons and nuclei play a crucial role in core-collapse supernovae, the spectacular explosions that mark the deaths of massive stars. Over ninety-nine percent of the energy released during such explosions is released as neutrinos, and it is believed that their production and interactions with matter provide a mechanism which drives the explosion to its conclusion. As such, accurate estimates for the rates of neutrino emission, absorption and scattering are key input for supernovae simulations. Our research presents the rst results for neutrino rates in supernovae based on Chiral Eective Field Theory (EFT) and contrasts them to the phenomenological models used in current simulations. We focus on the rate of neutrino-pair bremsstrahlung due to nucleon-nucleon scattering. This reaction produces all three generations of neutrinos through the process N + N ! N + N + + , and is a major source of and neutrinos. The Chiral EFT results are compared to rates based on scattering data to further demonstrate the improvement over rates which are currently used in supernova simulations. The rates may be well constrained between the Chiral EFT and scattering data results for densities < 1014 g cm3. This enables us to provide a simple t function representing our results for use in supernova simulations. Core-collapse supernovae are the birth places of neutron stars. Furthermore, the neutrino driven out ows are believed to be a site for the creation of elements heavier than iron. As such, an understanding of supernovae and the related neutrino emissions is fundamental to a broader comprehension of the universe, on both an astrophysical and an atomic scale.
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