Speaker
Description
Neutron stars are objects described by the quantum chromodynamics (QCD), which predict a deconfined quark phase for high densities. It is possible that quark matter can be reached in the core of neutron star surrounded by a hadronic phase. For an hybrid star, the two solar mass neutron star constraint requires a stiff equation of state (EoS) for intermediate densities that supports a soft core at high densities. We use the density-dependent meson-nucleon – DDME2 model for the hadronic phase and the Nambu–Jona-Lasinio SU(3) model with multiquark interaction for quark phase with a density-dependent vector coupling – $G_{\omega \omega}(\rho_B)$ – such that at high densities it strongly weakens. The choice of this coupling is based on the strong constraints imposed by perturbative QCD (pQCD). We use Bayesian inference to construct sets of quark EoS constrained by x-ray observational data from NICER, gravitational wave data from the binary neutron star merger GW170817. The Maxwell construction is applied for the deconfinement phase transition. We compare hybrid star model with a model with a $G_{\omega \omega}$ not depending on density. We can see how the multiquark parameters are changed by this new configuration and discuss the behavior of the speed of sound. The EoS built all satisfy pQCD constraints although the constraint did not enter the Bayesian inference.