Impact of dineutrons on nuclear compositions of a core-collapse supernova

Abstract

We study the nuclear compositions in the central region of a core-collapse supernova, assuming the existence of dineutrons ($^2n$) and tetraneutrons ($^4n$). At 100~ms after core bounce, ${}^2n$ and ${}^4n$ are more abundant than deuterons within radii of approximately 100 and 50~km, respectively. Compared to the model ignoring the existence of ${}^2n$ and ${}^4n$, the mass fraction of neutrons up to a radius of 100~km reduces, while the mass fractions of protons, deuterons, and $\rm{{}^4He}$ increase. Due to the uncertainties in the properties of $^2n$ and $^4n$, we investigate the influence of their binding energies on the nuclear composition. We find the binding energy of $^2n$ has only a modest effect on the overall composition, except for its own mass fraction, while that of $^4n$ has a negligible impact.