Search for extraterrestrial antineutrinos with the SNO+ detector

All antineutrinos observed to date have originated on Earth, as products of cosmic ray interactions in the atmosphere or nuclear decays, both in nuclear reactors and the planetary crust. We describe a search for extraterrestrial electron antineutrinos in an energy range of 10 MeV < E < 40 MeV using the SNO+ detector, for which the relatively large overburden and distance from operating reactors offer low backgrounds in a scintillator detector. We further present model-independent limits on the astrophysical flux, as well limits on MeV-scale dark matter self-annihilation rates.