Probing thermonuclear supernova explosions with neutrinos

TL;DR

This paper analyzes neutrino signals from type Ia supernova models, showing that neutrino signatures can distinguish between pure deflagration and delayed detonation explosion mechanisms, despite similar electromagnetic outputs.

Contribution

It introduces a method to differentiate supernova explosion models using neutrino signals, which was not previously demonstrated.

Findings

Neutrino signatures differ significantly between explosion models.

A pure deflagration produces a single neutrino peak, while delayed detonation shows two.

Future detectors could identify supernova explosion mechanisms via neutrino detection.

Abstract

Aims: We present neutrino light curves and energy spectra for two representative type Ia supernova explosion models: a pure deflagration and a delayed detonation. Methods: We calculate the neutrino flux from $\beta$ processes using nuclear statistical equilibrium abundances convoluted with approximate neutrino spectra of the individual nuclei and the thermal neutrino spectrum (pair+plasma). Results: Although the two considered thermonuclear supernova explosion scenarios are expected to produce almost identical electromagnetic output, their neutrino signatures appear vastly different, which allow an unambiguous identification of the explosion mechanism: a pure deflagration produces a single peak in the neutrino light curve, while the addition of the second maximum characterizes a delayed-detonation. We identified the following main contributors to the neutrino signal: (1) weak electron neutrino emission from electron captures (in particular on the protons Co55 and Ni56) and numerous beta-active nuclei produced by the thermonuclear flame and/or detonation front, (2) electron antineutrinos from positron captures on neutrons, and (3) the thermal emission from pair annihilation. We estimate that a pure deflagration supernova explosion at a distance of 1 kpc would trigger about 14 events in the future 50 kt liquid scintillator detector and some 19 events in a 0.5 Mt water Cherenkov-type detector. Conclusions: While in contrast to core-collapse supernovae neutrinos carry only a very small fraction of the energy produced in the thermonuclear supernova explosion, the SN Ia neutrino signal provides information that allows us to unambiguously distinguish between different possible explosion scenarios. These studies will become feasible with the next generation of proposed neutrino observatories.