Neutrino flux from collisions of red giant cores in globular clusters

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 and smoothed-particle hydrodynamics simulations of the final inspiral phase, we develop a semianalytical model to estimate the amount of hydrogen mixed into the cores, the energy release ( ≈ 4.28 × 10 49 erg ) that heats the remnant to T f ≈ 5.3 × 10 8 K , the magnetic field amplification ( B ≈ 1.77 × 10 10 G ), and the resulting neutrino flux. The predicted TeV–PeV neutrino signal may contribute to the diffuse IceCube neutrino flux; we estimate that the horizon at which a single neutrino event is expected on average at ≳ 100 TeV is ≈ 55 kpc for individual merger events. 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 F 18 offer a direct observational test of the detonation, (as sources within ∼ 4.4 pc would produce a neutrino flux exceeding the solar CNO neutrino background). The simultaneous emission of high-energy hadronic neutrinos, gravitational waves, and—if the optical depth permits ( τ T ∼ 10 14 in the core of the remnant)—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.