The Crimson Kiss of Two Giants: Helium Detonation and High-Energy Neutrino Production

TL;DR

This paper introduces erythrohenosis, a new astrophysical process involving helium core collisions in red giants, predicting high-energy neutrino emissions detectable by IceCube and proposing multimessenger observational signatures.

Contribution

It develops a semi-analytical model of helium core collisions, predicting neutrino fluxes and multimessenger signals, and links these events to observable high-energy neutrinos and gravitational waves.

Findings

Predicted neutrino flux matches IceCube observations.

A single event within 2 Mpc is detectable in TeV--PeV range.

Neutrinos from $^{18}$F decay provide a test for the model.

Abstract

The coalescence of degenerate helium cores during red giant collisions - a process we term erythrohenosis - introduces a novel class of transient astrophysical sources of high-energy neutrinos. Using stellar models generated with MESA and SPH simulations of the final inspiral phase, we develop a semi-analytical model to estimate the amount of hydrogen mixed into the cores, the energy release ($\approx 4.28 \times 10^{49}$ erg) that heats the remnant to $T_f \approx 5.3 \times 10^8$ K, the magnetic field amplification ($B \approx 1.77 \times 10^{10}$ G), and the resulting neutrino flux. We find that the predicted TeV--PeV neutrino signal can account for the diffuse neutrino flux observed by IceCube and demonstrate that a single merger event within $\sim 2$ Mpc would be detectable in this energy regime. Furthermore, we discuss the probability of a magnetized helium flash and assess the subsequent activation of the CNO cycle in the remnant core due to hydrogen mixing. In particular, neutrinos from the decay of $^{18}$F offer a direct observational test of the detonation. The simultaneous emission of high-energy hadronic neutrinos, gravitational waves, and -- if the optical depth permits -- an electromagnetic signal would constitute a unique multimessenger signature of red giant core collisions, positioning erythrohenosis events as exotic yet potentially observable phenomena in dense stellar systems.