Effects of a Brueckner-Hartree-Fock-corrected effective mass on speed of sound, conformality, and observables of dark matter-admixed neutron stars

TL;DR

This paper develops a neutron star equation of state incorporating dark matter and BHF-derived effective masses, revealing impacts on star compactness, sound speed, and conformality, with implications for dark matter presence in neutron stars.

Contribution

It introduces a novel mixed-model equation of state using BHF-informed effective masses, linking dark matter effects to neutron star properties and observational constraints.

Findings

Increased stellar compactness and lighter mass-radius configurations.

Sound speed behavior aligns with neutron star data and approaches conformal bounds.

Tension with bounds on heavier pulsars suggests need for further dark matter studies.

Abstract

We construct an equation of state describing cold and dense matter in the core of neutron stars which includes an admixture of fermionic dark matter and incorporates nucleon effective masses derived from the relativistic Brueckner-Hartree-Fock (BHF) many-body approach within a relativistic mean-field model. Such a BHF-informed mixed-model approach increases stellar compactness, with mass-radius configurations which are consistent with smaller, lighter pulsars. The model displays the expected non-monotonic behavior of sound speed hinted at by neutron star data, and is closer to the conformal bound at maximum mass. We find that the model displays tension with bounds on heavier pulsars, suggesting that the hypothesis of an aggregated dark component in neutron stars needs further critical study.