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Content archived on 2024-05-29

Neutrinos in Astrophysics

Final Activity Report Summary - ASTRONUS (Neutrinos in Astrophysics)

The project aim was to study properties of turbulent matter density fluctuations and its influence on supernovae neutrino oscillations. The turbulent motion of matter behind the shock wave is created during the supernova explosion. The scales and strength of turbulent matter density fluctuations were extracted from the numerical simulations of supernova dynamics.

The obtained results on matter density fluctuations in supernova were relevant not only for the analyses of supernova neutrino data but also for various astrophysical phenomena and, in particular, for the acceleration of cosmic rays. These results were used later in numerical calculations of supernova neutrino spectra accounting for matter density fluctuations generated during explosions. They demonstrated a significant dependence of neutrino spectra for some ranges of neutrino parameters.

Additional tasks were also studied, with some of them being related to the main topic of the project. As such, a new method to probe non-standard neutrino-quark interactions using coherent neutrino scattering off nuclei was proposed. Relevant results had an important impact on the neutrino flavour conversion in supernovae.

We also showed that future neutrino experiments searching for diffuse supernovae neutrino flux could not distinguish diffuse and solar antineutrino flux in the energy range below 15 MeV. A significant statistics of neutrino events of energies above 15 MeV was needed.

Furthermore, the influence of stellar, or solar, magnetic fields on the spectra of stellar (solar) gravity modes was considered. Observed displacements of spectra of solar g-mode candidates were explained in the framework of the model with a central solar magnetic field.

Finally, the possibility to detect a signal of gamma-ray source located behind the Sun using gamma-ray observatory in the models with axion-like particles was proposed. It was shown that next generation gamma-ray observatories would be able to test such a phenomenon.