Monte Carlo Study of Supernova Neutrino Spectra Formation
| Autor: | Georg G. Raffelt, Mathias Th. Keil, Hans-Thomas Janka |
|---|---|
| Rok vydání: | 2002 |
| Předmět: |
Elastic scattering
Physics Annihilation Scattering Astrophysics::High Energy Astrophysical Phenomena High Energy Physics::Phenomenology Astrophysics (astro-ph) Bremsstrahlung FOS: Physical sciences Astronomy and Astrophysics Electron Astrophysics Nuclear physics High Energy Physics - Phenomenology Recoil High Energy Physics - Phenomenology (hep-ph) Space and Planetary Science High Energy Physics::Experiment Neutrino Nucleon |
| DOI: | 10.48550/arxiv.astro-ph/0208035 |
| Popis: | The neutrino flux and spectra formation in a supernova core is studied by using a Monte Carlo code. The dominant opacity contribution for nu_mu and nu_tau is elastic scattering on nucleons. In addition we switch on or off a variety of processes which allow for the exchange of energy or the creation and destruction of neutrino pairs, notably nucleon bremsstrahlung, the e^+ e^- pair annihilation process and nu_e-bar nu_e -> nu_{mu,tau} nu_{mu,tau}-bar, recoil and weak magnetism in elastic nucleon scattering, elastic scattering on electrons and positrons and elastic scattering on electron neutrinos and anti-neutrinos. The least important processes are neutrino-neutrino scattering and e^+ e^- annihilation. The formation of the spectra and fluxes of nu_mu is dominated by the nucleonic processes, i.e. bremsstrahlung and elastic scattering with recoil, but also nu_e nu_e-bar annihilation and nu_mu e^\pm scattering contribute significantly. When all processes are included, the spectral shape of the emitted neutrino flux is always ``pinched,'' i.e. the width of the spectrum is smaller than that of a thermal spectrum with the same average energy. In all of our cases we find that the average nu_mu-bar energy exceeds the average nu_e-bar energy by only a small amount, 10% being a typical number. Weak magnetism effects cause the opacity of nu_mu to differ slightly from that of nu_mu-bar, translating into differences of the luminosities and average energies of a few percent. Depending on the density, temperature, and composition profile, the flavor-dependent luminosities L_{nu_e}$, L_{nu_e-bar}, and L_{nu_mu} can mutually differ from each other by up to a factor of two in either direction. 33 pages, 16 eps-figs, submitted to ApJ. Sections added: weak magnetism, discussion of different analytic fits to the spectra and detailed spectral shape |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|