Upcoming Seminars

Affiliation:North Carolina State University
Time: 3 pm
Location: N288 ESC

Neutrino Flavor Conversion in Supernovae and Neutron Star Mergers

Neutrinos play an important role in the dynamics and outcomes of extreme astrophysical events such as core-collapse supernovae (CCSN) and neutron star mergers (NSM). Of particular interest is the possibility of neutrino flavor conversions. It is well known that neutrinos undergo vacuum oscillations between flavor states, but in these matter-dense environments, oscillations are modified through coherent forward scattering off the background fluid or even the neutrinos themselves. This scattering adds terms to the effective potential in the equation of motion for the neutrino distribution, leading to flavor instabilities under certain conditions. Among these are the fast flavor instability (FFI), and the collisional flavor instability (CFI). These trigger flavor conversion in the neutrino distributions, and thus alter the total rates for charged-current reactions with the background fluid. 

However, incorporating flavor conversion in global CCSN or NSM simulations remains a significant challenge. Large differences in the time and length scales between conversions and the simulations make including them in the numerical calculations intractable. One approach is to use subgrid models that can capture flavor conversion by mapping the neutrino distribution from initial to asymptotic states. Thus, to accurately characterize flavor conversions and test the subgrid models and their assumptions, we run local, conversion-scale simulations at select points with flavor instabilities. These simulations resolve instability growth rates, flavor conversion dynamics, and, most importantly, the asymptotic states of the neutrino distributions.

Biographical Sketch:

Christian graduated in Physics and Astronomy from BYU in 2022 and is now a PhD student NC State.

Time: 4:00 PM
Location: C215 ESC

Affiliation:BYU Physics and Astronomy
Time: 4:00 PM
Location: C215 ESC