Global properties of nuclei at finite-temperature within the covariant energy density functional theory

TL;DR

This study performs a comprehensive analysis of nuclear properties at finite temperatures using the covariant energy density functional theory, revealing significant effects near the neutron-drip line and as temperature increases.

Contribution

First global finite-temperature calculations of nuclear properties across a wide range of nuclei using the relativistic Hartree-Bogoliubov model with vapor subtraction.

Findings

Continuum states significantly affect nuclei near the neutron-drip line at T≈1 MeV.

Finite temperature moderately reduces pairing correlations and nuclear deformations up to 1 MeV.

Higher temperatures lead to pronounced reduction in shell effects and nuclear structure changes.

Abstract

In stellar environments nuclei appear at finite temperatures, becoming extremely hot in core-collapse supernovae and neutron star mergers. However, due to theoretical and computational complexity, most model calculations of nuclear properties are performed at zero temperature, while those existing at finite temperatures are limited only to selected regions of the nuclide chart. In this study we perform the global calculation of nuclear properties for even-even $8 \leq Z \leq 104$ nuclei at temperatures in range $0\le T \le 2$ MeV. Calculations are based on the finite temperature relativistic Hartree-Bogoliubov model supplemented by the Bonche-Levit-Vautherin vapor subtraction procedure. We find that near the neutron-drip line the continuum states have significant contribution already at moderate temperature $T\approx 1$ MeV, thus emphasising the necessity of the vapor subtraction procedure. Results include neutron emission lifetimes, quadrupole deformations, neutron skin thickness, proton and neutron pairing gaps, entropy and excitation energy. Up to the temperature $T\approx 1$ MeV nuclear landscape is influenced only moderately by the finite-temperature effects, mainly by reducing the pairing correlations. As the temperature increases further, the effects on nuclear structures become pronounced, reducing both the deformations and the shell effects.