# GR Effects in Supernova Neutrino Flavor Transformation

## TL;DR

This paper investigates how general relativistic effects like time dilation, energy redshift, and trajectory bending influence neutrino flavor transformations in supernovae, showing these effects can alter flavor evolution and potentially impact nucleosynthesis.

## Contribution

It quantifies the impact of GR effects on neutrino flavor transformation during supernova phases using multi-angle calculations, highlighting their significance during the cooling phase.

## Key findings

- GR effects increase the neutrino self-interaction potential by up to three times.
- During the accretion phase, GR effects are small and mainly delay decoherence.
- In the cooling phase, GR effects delay bipolar oscillations, possibly affecting nucleosynthesis.

## Abstract

The strong gravitational field around a proto-neutron star can modify the neutrino flavor transformations that occur above the neutrinosphere via three General Relativistic (GR) effects: time dilation, energy redshift, and trajectory bending. Depending on the compactness of the central object, the neutrino self-interaction potential is up to three times as large as that without GR principally due to trajectory bending which increases the intersection angles between different neutrino trajectories, and time dilation which changes the fluxes. We determine whether GR effects are important for flavor transformation during the different epochs of a supernova by using multi-angle flavor transformation calculations and consider a density profile and neutrino spectra representative of both the accretion and cooling phases. We find the GR effects are smaller during the accretion phase due to low compactness of the proto-neutron star and merely delay the decoherence; the neutrino bipolar oscillations during the cooling phase are also delayed due to the GR effects but the delay may be more important because the delay occurs at radii where it might alter the nucleosynthesis in the neutrino driven wind.