Weak interaction rates of $sd$-shell Urca pairs in stellar environment using a shell-model approach

TL;DR

This paper calculates weak interaction rates of sd-shell nuclei in stellar environments using shell-model approaches, including ab initio and phenomenological interactions, and evaluates their impact on stellar cooling and Urca processes.

Contribution

It provides detailed weak rate calculations for sd-shell nuclei in stellar conditions, incorporating screening effects and intrinsic cooling, using both ab initio and phenomenological shell-model interactions.

Findings

Weak rates are computed across a grid of density and temperature.

Urca densities are identified for specific nuclei.

Cooling strengths in neutron star crusts are evaluated.

Abstract

In this work, the weak interaction rates of $sd$-shell nuclei in the hot and dense stellar environment are calculated using the shell model. The {\it ab initio} effective interactions are employed for the calculation of Gamow-Teller strengths and weak rates in addition to the phenomenological interaction. The weak rates are evaluated in a fine grid of density and temperature. The electron capture and $\beta^-$-decay rates of Urca pairs of nuclei with $A = 23, 25, 29, 31$ and 33 are evaluated as a function of $\log_{10} \rho Y_e$ and the corresponding Urca density is obtained. The screening effects are also included for the evaluation of these stellar weak rates. In addition, the intrinsic cooling strength is evaluated for $A=29,31$ and 33 Urca pairs in neutron star crusts. The stellar weak rates, along with the neutrino energy emitted and the gamma heat production, are tabulated for $A = 29-39$ nuclei.