Baryonic dense matter in view of gravitational-wave observations

TL;DR

This paper investigates how different theoretical models of dense nuclear matter align with recent gravitational-wave and neutron star observations, highlighting the viability of density-dependent schemes and the role of exotic particles.

Contribution

It compares covariant density functional models, specifically Non-Linear and Density-Dependent schemes, to astrophysical constraints, showing density-dependent models better match observations and experiments.

Findings

Density-dependent models align with gravitational-wave and neutron star data.

Non-linear models largely fail to support observational constraints.

Including heavier non-strange baryons improves model agreement with observations.

Abstract

The detection of gravitational waves from the merger of binary neutron stars events (GW170817, GW190425) and subsequent estimations of tidal deformability play a key role in constraining the behaviour of dense matter. In addition, massive neutron star candidates ($\sim 2 M_{\odot}$) along with NICER mass-radius measurements also, set sturdy constraints on the dense matter equation of state. Strict bounds from gravitational waves and massive neutron stars observations constrain the theoretical models of nuclear matter comportment at large density regimes. On the other hand, model parameters providing the highly dense matter response are bounded by nuclear saturation properties. This work analyses coupling parametrizations from two classes based on covariant density functional models: Non-Linear and Density-Dependent schemes. Considering these constraints together, we study possible models and parametrization schemes with the feasibility of exotic degrees of freedom in dense matter which go well with the astrophysical observations as well as the terrestrial laboratory experiments. We show that most parametrizations with non-linear schemes do not support the observations and experiments while density-dependent scheme goes well with both. Astrophysical observations are well explained if the inclusion of heavier non-strange baryons is considered as one fraction of the dense matter particle spectrum.