Nuclear matter EOS with light clusters within the mean-field approximation

TL;DR

This paper investigates how light nuclear clusters form and dissolve in neutron star crusts using the mean-field approximation, impacting astrophysical phenomena like cooling and gravitational waves.

Contribution

It models the dissolution density of light clusters in nuclear matter within the mean-field framework, analyzing the effects of clusters-meson couplings.

Findings

Dissolution density depends on clusters-meson couplings.

Light clusters form at low densities and moderate temperatures.

Clusters dissolve at densities above approximately 0.1 times nuclear saturation density.

Abstract

The crust of a neutron star is essentially determined by the low-density region ($\rho<\rho_0\approx0.15-0.16\unit{fm}^{-3}$) of the equation of state. At the bottom of the inner crust, where the density is $\rho\lesssim0.1\rho_0$, the formation of light clusters in nuclear matter will be energetically favorable at finite temperature. At very low densities and moderate temperatures, the few body correlations are expected to become important and light nuclei like deuterons, tritons, helions and $\alpha$-particles will form. Due to Pauli blocking, these clusters will dissolve at higher densities $\rho\gtrsim 0.1\rho_0$. The presence of these clusters influences the cooling process and quantities, such as the neutrino emissivity and gravitational waves emission. The dissolution density of these light clusters, treated as point-like particles, will be studied within the Relativistic Mean Field approximation. In particular, the dependence of the dissolution density on the clusters-meson couplings is studied.