Presupernova neutrinos: directional sensitivity and prospects for progenitor identification

Understand

We explore the potential of current and future liquid scintillator neutrino detectors of O (10) kt mass to localize a pre-supernova neutrino signal in the sky.

• In the hours preceding the core collapse of a nearby star (at distance D < 1 kpc), tens to hundreds of inverse beta decay events will be recorded, and their reconstructed topology in the detector can be used to estimate the direction to the star.
• Although the directionality of inverse beta decay is weak (~8% forward-backward asymmetry for currently available liquid scintillators), we find that for a fiducial signal of 200 events (which is realistic for Betelgeuse), a positional error of ~60 degrees can be achieved, resulting in the possibility to narrow the list of potential stellar candidates to less than ten, typically.
• For a configuration with improved forward-backward asymmetry (~40%, as expected for a lithium-loaded liquid scintillator), the angular sensitivity improves to ~15 degrees, and - when a distance upper limit is obtained from the overall event rate - it is in principle possible to uniquely identify the progenitor star.