Baryonic dense matter in view of gravitational-wave observations

• Published in: Monthly notices of the Royal Astronomical Society Vol. 507; no. 2; pp. 2991 - 3004
• Main Authors: Thapa, Vivek Baruah, Kumar, Anil, Sinha, Monika
• Format: Journal Article
• Language: English
• Published: Oxford University Press 01.10.2021
• Subjects: equation of state; gravitational waves; dense matter; stars: neutron
• ISSN: 0035-8711; 1365-2966
• DOI: 10.1093/mnras/stab2327

ABSTRACT The detection of gravitational waves (GWs) from the merger of binary neutron star (NS) events (GW170817 and GW190425) and subsequent estimations of tidal deformability play a key role in constraining the behaviour of dense matter. In addition, massive NS candidates (∼2 M⊙) along with NICER mass–radius measurements also set sturdy constraints on the dense matter equation of state. Strict bounds from GWs and massive NS 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.