Low-energy supernovae bounds on sterile neutrinos

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 (sin2θ) from SN arise from SN1987A energy-loss, requiring Eloss < 1052 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 ∼ 1050 erg. Focusing on sterile neutrino mixing only with tau neutrino, for heavy sterile masses ms in the range 100 – 500 MeV, we find stringent constraints on sin2θτ 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 (sin2θμ).