Observing Supernova Neutrino Light Curves with Super-Kamiokande. III. Extraction of Mass and Radius of Neutron Stars from Synthetic Data

Neutrinos are guaranteed to be observable from the next Galactic supernova (SN). Optical light and gravitational waves are also observable, but may be difficult to observe if the location of the SN in the Galaxy or the details of the explosion are unsuitable. The key to observing the next SN is to first use neutrinos to understand various physical quantities and then link them to other signals. In this paper, we present Monte Carlo sampling calculations of neutrino events from Galactic SN explosions observed with Super-Kamiokande. The analytical solution of neutrino emission, which represents the long-term evolution of the neutrino light curve from SNe, is used as a theoretical template. It gives the event rate and event spectrum through inverse beta decay interactions with explicit model parameter dependence. Parameter estimation is performed on these simulated sample data by fitting least squares using the analytical solution. The results show that the mass, radius, and total energy of a remnant neutron star produced by an SN can be determined with an accuracy of ∼0.1 M o˙, ∼1 km, and ∼1051 erg, respectively, for a Galactic SN at 8 kpc.