Exploring hybrid equation of state with constraints from tidal deformability of GW170817

TL;DR

This paper develops a hybrid equation of state combining a novel quark model and relativistic mean-field theory, analyzing its impact on neutron star properties and tidal deformability constraints from GW170817.

Contribution

It introduces a new self-consistent two-flavor Nambu-Jona-Lasinio model with a vector channel contribution and explores its effects on hybrid EOS and neutron star observables.

Findings

Hybrid EOS can produce neutron stars exceeding 2 solar masses.

Increasing the vector channel parameter softens the EOS in medium pressure.

Calculated tidal deformability aligns with GW170817 constraints.

Abstract

With a interpolation method on the P-$\mu$ plane, a hybrid equation of state is explored. The quark phase is described by our newly developed self-consistent two-flavor Nambu$-$Jona-Lasinio model. It retains the contribution from the vector channel in the Fierz-transformed Lagrangian by introducing a weighting parameter $\alpha$ [Chin. Phys. C \textbf{43}, 084102 (2019)]. In the hadron phase we use the relativistic mean-field theory. We study the dependence of hybrid EOS and mass-radius relation on $\alpha$. It is found that increasing $\alpha$ makes the hybrid EOS softer in the medium pressure. We can get stellar mass larger than $2M_\odot$. Further, we calculate the tidal deformability $\tilde\Lambda$ for binary stars and compare with recent analysis GW170817 [Phys. Rev. X \textbf{9}, 011001 (2019)].