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

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.

Submitted