The Cosmic MeV Neutrino Background as a Laboratory for Black Hole Formation

TL;DR

This paper discusses how the cosmic MeV neutrino background can serve as a tool to study black hole formation, emphasizing the importance of redshift-dependent collapse fractions and their impact on neutrino detectability.

Contribution

It introduces the idea that the fraction of stars collapsing into black holes increases with redshift, affecting neutrino flux predictions and detection prospects.

Findings

Neutrino flux from black hole-forming collapses is higher at greater redshifts.

Detectability of the cosmic neutrino background improves with redshift-dependent models.

Neutrino detectors can probe black hole formation history after isolating supernova signals.

Abstract

Calculations of the cosmic rate of core collapses, and the associated neutrino flux, commonly assume that a fixed fraction of massive stars collapse to black holes. We argue that recent results suggest that this fraction instead increases with redshift. With relatively more stars vanishing as "unnovae" in the distant universe, the detectability of the cosmic MeV neutrino background is improved due to their hotter neutrino spectrum, and expectations for supernova surveys are reduced. We conclude that neutrino detectors, after the flux from normal SNe is isolated via either improved modeling or the next Galactic SN, can probe the conditions and history of black hole formation.