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The Effects of Massive Neutrino Self-Interactions on the Cosmic Microwave Background and Large Scale Structure
Research Mentor and Department
Exploring potential effects of the neutrino’s mass can reveal new and exciting knowledge about the universe. In the standard cosmological model, neutrinos decoupled from the primordial plasma at T ∼ 1.5 MeV and then began free-streaming. However, the presence of new interactions in the neutrino sector, such as those responsible for neutrino mass, can significantly delay the onset of neutrino free-streaming. These effects alter the anisotropic stress history, which is measurable with observables like the Cosmic Microwave Background (CMB) and matter clustering. For the first time, we study the cosmological physics of self-interacting neutrinos while self-consistently taking into account the neutrino mass. We present the results of numerically implementing the mass corrected collision term in the Boltzmann equation. We find the neutrino mass and self-interaction have an additive damping effect on the matter power spectrum for small scales and alter the phase and amplitude of the CMB temperature power spectrum.