Neutrino Constraints on Black Hole Formation in M31

TL;DR

This study addresses how neutrinos can reveal black-hole formation in failed core-collapse supernovae, motivated by the M31-2014-DS1 candidate. It synthesizes general-relativistic simulations across multiple nuclear EOSs to predict neutrino luminosities, spectra, and the abrupt cutoff at BH formation, then translates these predictions into expected events for Super-Kamiokande and compares them to a decade of non-detections, including the role of MSW flavor transformations and mass ordering. The results show that SK non-detections exclude portions of the EOS/progenitor parameter space and highlight the strong influence of the EOS on the neutrino signal, with higher maximum PNS masses producing longer, more energetic emissions. Looking ahead, Hyper-Kamiokande promises dramatic advances, enabling EOS discrimination and potential neutrino-mass ordering studies for extragalactic failed SNe, and establishing neutrino astronomy as a powerful probe of BH formation in stellar collapses.

Abstract

We investigate neutrino signals associated with black hole formation resulting from the gravitational collapse of massive stars, motivated by the candidate failed supernova M31-2014-DS1 in the Andromeda Galaxy (M31). By compiling numerical simulation results for stellar collapse, we predict the expected neutrino emission and compare these predictions with observational limits from Super-Kamiokande (SK). The simulations reveal a characteristic precursor signal consisting of a short, intense burst whose average neutrino energy rises rapidly and then ceases abruptly once the black hole forms. We examine several nuclear equations of state, specifically the Lattimer \& Swesty, Shen, Togashi, and SFHo models, to evaluate how the emission depends on neutron-star properties and nuclear-physics uncertainties. Comparison of the predicted event counts with SK's non-detection of neutrinos coincident with M31-2014-DS1 already rules out part of the model space and highlights the sensitivity of current neutrino detectors to both progenitor mass and the EOS. These findings demonstrate the capability of neutrino astronomy to probe core collapse and black hole formation in failed supernova scenarios.

Figures (2)

• Figure 1: Total emitted electron antineutrino energy $E_{\bar{\nu}_e}$ versus mean energy $\langle\varepsilon_{\bar{\nu}_e}\rangle$ predicted by black-hole-forming core-collapse simulations. The shaded bands indicate regions that would have produced $\ge 2$ correlated events in SK with probabilities of 50 %, 68 %, 95 %, and 99 % (light to dark blue), assuming Poisson statistics for a source at the distance of M31. Filled circles show individual simulation results for seven nuclear equations of state (EOS): LS180, LS220, DD2F RDF-1.7, SFHo, Togashi, Shen-TM1e, and Shen-TM1. Both grey tone and symbol size encode the maximum gravitational mass of a non-rotating protoneutron star supported by each EOS: lighter symbols correspond to softer EOSs with the maximum gravitational mass of protoneutron star with thermal correction, $M^{\max}_{s=4}=2.0\text{--}2.1\,M_{\odot}$ (LS180, LS220), whereas darker symbols mark EOSs with $M^{\max}_{s=4}=2.5\text{--}2.6\,M_{\odot}$ (Shen-TM1e, Shen-TM1). Models that lie outside the shaded regions, where fewer than two events would be expected, remain compatible with the SK non-detection, illustrating the strong dependence of the predicted neutrino signal on EOS stiffness and the associated maximum neutron-star mass.
• Figure 2: The same as Figure \ref{['fig:fig']}, but with neutrino oscillation taken into account. Triangles indicate model predictions under normal (upward triangles) and inverted (downward triangles) neutrino mass orderings.