Influence of the nuclear symmetry energy slope on observables of compact stars with $\Delta$-admixed hypernuclear matter

TL;DR

This study explores how the slope of nuclear symmetry energy influences neutron star properties, revealing that lower symmetry energy slopes promote earlier $\Delta$-resonance appearance and affect observable star characteristics.

Contribution

It introduces a covariant density functional approach to analyze the impact of symmetry energy slope on neutron star matter with $\Delta$-resonances and hyperons, highlighting the role of non-linear and density-dependent models.

Findings

Smaller symmetry energy slopes favor earlier $\Delta$-resonance appearance.

Larger symmetry energy slopes lead to converging tidal deformability values.

The equation of state affects neutron star mass-radius and tidal response predictions.

Abstract

In this work, we study the effects of nuclear symmetry energy slope on neutron star dense matter equation of state and its impact on neutron star observables (mass-radius, tidal response). We construct the equation of state within the framework of covariant density functional theory implementing coupling schemes of non-linear and density-dependent models with viability of heavier non-nucleonic degrees of freedom. The slope of symmetry energy parameter ($L_{\text{sym}}$) is adjusted following density-dependence of isovector meson coupling to baryons. We find that smaller values of $L_{\text{sym}}$ at saturation favour early appearance of $\Delta$-resonances in comparison to hyperons leading to latter's threshold at higher matter densities. We also investigate the dependence of $L_{\text{sym}}$ on tidal deformability and compactness parameter of a $1.4~M_\odot$ neutron star for different equation of states and observe similar converging behaviour for larger $L_{\text{sym}}$ values.