Results From Core-Collapse Simulations with Multi-Dimensional, Multi-Angle Neutrino Transport

TL;DR

This paper presents advanced 2D multi-angle neutrino transport simulations of core-collapse supernovae, revealing how neutrino emissions relate to shock oscillations and how rotation affects neutrino signals, with implications for detection.

Contribution

It provides the first detailed multi-angle neutrino transport results for both nonrotating and rotating supernova models, highlighting the importance of multi-angle effects and rotation on neutrino signals.

Findings

Neutrino radiation fields vary less with angle than matter quantities.

Neutrino flux fluctuations are detectable within ~10 kpc in nonrotating models.

Rapid rotation causes strong asymmetries in neutrino emission and light curves.

Abstract

We present new results from the only 2D multi-group, multi-angle calculations of core-collapse supernova evolution. The first set of results from these calculations was published in Ott et al. (2008). We have followed a nonrotating and a rapidly rotating 20 solar mass model for ~400 ms after bounce. We show that the radiation fields vary much less with angle than the matter quantities in the region of net neutrino heating. This obtains because most neutrinos are emitted from inner radiative regions and because the specific intensity is an integral over sources from many angles at depth. The latter effect can only be captured by multi-angle transport. We then compute the phase relationship between dipolar oscillations in the shock radius and in matter and radiation quantities throughout the postshock region. We demonstrate a connection between variations in neutrino flux and the hydrodynamical shock oscillations, and use a variant of the Rayleigh test to estimate the detectability of these neutrino fluctuations in IceCube and Super-K. Neglecting flavor oscillations, fluctuations in our nonrotating model would be detectable to ~10 kpc in IceCube, and a detailed power spectrum could be measured out to ~5 kpc. These distances are considerably lower in our rapidly rotating model or with significant flavor oscillations. Finally, we measure the impact of rapid rotation on detectable neutrino signals. Our rapidly rotating model has strong, species-dependent asymmetries in both its peak neutrino flux and its light curves. The peak flux and decline rate show pole-equator ratios of up to ~3 and ~2, respectively.