# Do “neutrino supernovae” exist?

Core collapse supernovae release most of their energy in the form of neutrinos. About 1% of the neutrinos are absorbed by the thick outer envelope which powers a spectacular supernova explosion.

Core collapse can also happen in white dwarfs. According to this answer, white dwarfs made of light elements (He, C) explode upon reaching the Chandrasekhra mass limit, while white dwarfs consisting of heavy elements (O, Ne, Mg) collapse into neutron stars. The collapse is not much different than the core collapse of massive stars, except that the white dwarfs are not buried under a thick atmosphere. As a result, neutrinos will just escape freely with little absorption.

Does that mean such collapses will result in “neutrino supernovae” (in analogy with neutron bombs), with minimal electromagnetic emission?

In type II supernovae the neutrinos are not absorbed by the thick outer envelope. They are absorbed, briefly, in the inner few tens of km of the collapsed core at nuclear densities ($$\geq 10^{17}$$ kg/m$$^{-3}$$). From that point of view, a supernova instigated by accretion-induced-collapse (AIC) of a massive white dwarf will be no different to a core-collapse supernova.
AIC supernovae are though expected to be relatively faint and short-lived in optical terms - the amount of mass ejected is small and contains little of the radioactive Nickel that powers type Ia supernovae. Piro & Thompson (2014) estimate that the absolute visual magnitude of such an event would peak at just $$M_V \sim -13$$ , which is about 100-1000 times fainter than most type Ia and type II supernovae, and would fade on timescales of 1-2 days. However, if the AIC is triggered by accretion from a close companion, they show that the blast wave will shock-hear the envelope of the companion causing the transient to be more luminous by factor of $$\sim 10-100$$ and extending the timescale of emission by a few days.