Low-Energy Supernovae Bounds on Sterile Neutrinos

TL;DR

This paper introduces a new bound on sterile neutrino properties based on energy deposition in supernovae, providing tighter constraints than previous energy-loss limits, especially for certain mass ranges and mixing angles.

Contribution

It presents a novel supernova-based bound on sterile neutrino parameters from decay energy deposition, improving constraints for heavy sterile neutrinos in the 100-500 MeV range.

Findings

Stringent constraints on $ heta_\tau^2$ for 100-500 MeV sterile neutrinos.

Bounds are two orders of magnitude stronger than SN1987A energy-loss limits.

Applicable to sterile neutrino mixing with muons as well.

Abstract

Sterile neutrinos can be produced through mixing with active neutrinos in the hot, dense core of a core-collapse supernova (SN). The standard bounds on the active-sterile mixing ($\sin^2 \theta$) from SN arise from SN1987A energy-loss, requiring $E_{\text{loss}}<10^{52}~{\rm erg}$. In this work, we discuss a novel bound on sterile neutrino parameter space arising from the energy deposition through its decays inside the SN envelope. Using the observed underluminous SN IIP population, this energy deposition is constrained to be below $\sim 10^{50}~{\rm erg}$. Focusing on sterile neutrino mixing only with tau neutrino, for heavy sterile masses $m_s$ in the range $100$-$500$ MeV, we find stringent constraints on $\sin^2 \theta_\tau$ reaching two orders of magnitude lower than those from the SN1987A energy loss argument, {thereby probing the mixing angles required for Type-I seesaw mechanism}. Similar bounds will also be applicable to sterile mixing only with muons ($\sin^2 \theta_\mu$).