Pre-supernova neutrino emissions from ONe cores in the progenitors of core-collapse supernovae: are they distinguishable from those of Fe cores?

摘要

Aiming to distinguish two types of progenitors of core collapse supernovae,i.e., one with a core composed mainly of oxygen and neon (abbreviated as ONecore) and the other with an iron core (or Fe core), we calculated theluminosities and spectra of neutrinos emitted from these cores prior togravitational collapse, taking neutrino oscillation into account. We found thatthe total energies emitted as $\bar{\nu}_e$ from the ONe core are $\lesssim10^{46}\ {\rm erg}$, which is much smaller than $\sim 10^{47}\ {\rm erg}$ forFe cores. The average energy, on the other hand, is twice as large for the ONecore as those for the Fe cores. The neutrinos produced by the plasmon decays inthe ONe core are more numerous than those from the electron-positronannihilation in both cores but they have much lower average energies $\lesssim1\ {\rm MeV}$. Although it is difficult to detect the pre-supernova neutrinosfrom the ONe core even if it is located within 200$\ $pc from the earth, weexpect $ \sim 9 - 43$ and $\sim 7 - 61$ events for Fe cores at KamLAND andSuper-Kamiokande, respectively, depending on the progenitor mass andneutrino-mass hierarchy. These numbers might be increased by an order ofmagnitude if we envisage next-generation detectors such as JUNO. We will hencebe able to distinguish the two types of progenitors by the detection ornon-detection of the pre-supernova neutrinos if they are close enough($\lesssim1\ {\rm kpc}$).