A comparative study of statistical models for nuclear equation of state of stellar matter

TL;DR

This study compares three statistical models for the nuclear equation of state in stellar matter during supernovae, highlighting similarities and differences in thermodynamics and nuclear distributions due to varying nuclear physics assumptions.

Contribution

It provides a comparative analysis of different nuclear physics inputs in statistical models for stellar matter EOS at subnuclear densities.

Findings

Thermodynamical quantities are similar across models except at high densities and low temperatures.

Mass and isotopic distributions vary significantly depending on nuclear properties assumptions.

Model differences are linked to uncertainties in medium effects and nuclear structure modeling.

Abstract

We compare three different statistical models for the equation of state (EOS) of stellar matter at subnuclear densities and temperatures (0.5-10 MeV) expected to occur during the collapse of massive stars and supernova explosions. The models introduce the distributions of various nuclear species in nuclear statistical equilibrium, but use somewhat different nuclear physics inputs. It is demonstrated that the basic thermodynamical quantities of stellar matter under these conditions are similar, except in the region of high densities and low temperatures. We demonstrate that mass and isotopic distributions have considerable differences related to the different assumptions of the models on properties of nuclei at these stellar conditions. Overall, the three models give similar trends, but the details reflect the uncertainties related to the modeling of medium effects, such as the temperature and density dependence of surface and bulk energies of heavy nuclei, and the nuclear shell structure effects. We discuss importance of new physics inputs for astrophysical calculations from experimental data obtained in intermediate energy heavy-ion collisions, in particular, the similarities of the conditions reached during supernova explosions and multifragmentation reactions.