Impact of Rotation on Neutrino Emission and Relic Neutrino Background from Population III Stars

TL;DR

This study investigates how rotation influences neutrino emission from Population III stars, revealing that rotation enhances neutrino luminosities and energies, potentially making relic neutrino backgrounds detectable and useful for understanding early star formation.

Contribution

The paper presents the first detailed two-dimensional simulations showing the impact of rotation on neutrino emission from Pop III stars, highlighting differences from spherical collapse models.

Findings

Rotation increases neutrino luminosity and energy.

Rotational flattening enlarges the inner core, boosting neutrino emission.

Relic neutrino background from Pop III stars can dominate below a few MeV.

Abstract

We study the effects of rotation on the neutrino emission from Population III (Pop III) stars by performing a series of two-dimensional rotational collapse simulations of Pop III stellar cores. Our results show that rotation enhances the neutrino luminosities and the average energies of emitted neutrinos. This is because the thermalized inner core, which is the dominant neutrino source from Pop III stars, can be enlarged, due to rotational flattening, enough to extend the inner core outside the neutrinospheres. This is in sharp contrast to the case of spherical collapse, in which the case of inner core shrinks deeper inside the neutrinospheres before black hole formation, which hinders the efficient neutrino emission. In the case of rotational core-collapse, the emitted neutrino energies are found to become larger in the vicinity near the pole than the ones near the equatorial plane. These factors make the emergent neutrino spectrum broader and harder than the spherical collapse case. By computing the overall neutrino signals produced by the ensemble of individual rotating Pop III stars, we find that the amplitudes of the relic neutrinos, depending on their star formation rates, can dominate over the contributions from ordinary core-collapse supernovae below a few MeV. A detection of this signal could be an important tool to probe star formation history in the early universe.