Constraints on the phase transition and nuclear symmetry parameters from PSR J 0740 + 6620 and multimessenger data of other neutron stars

Recently, the radius of neutron star (NS) PSR $\mathrm{J}0740+6620$ was measured by Neutron Star Interior Composition Explorer (NICER), and an updated measurement of neutron skin thickness of $^{208}\mathrm{Pb}$ (${R}_{\mathrm{skin}}^{208}$) was reported by the PREX-II experiment. These new measurements can help us better understand the unknown equation of state (EOS) of dense matter. In this work, we adopt a hybrid parameterization method, which incorporates the nuclear empirical parameterization and some widely used phenomenological parameterizations, to analyze the results of nuclear experiments and astrophysical observations. With the joint Bayesian analysis of GW170817, PSR $\mathrm{J}0030+0451$, and PSR $\mathrm{J}0740+6620$, the parameters that characterize the ultradense matter EOS are constrained. We find that the slope parameter $L$ is approximately constrained to ${70}_{\ensuremath{-}18}^{+21}\text{ }\text{ }\mathrm{MeV}$, which predicts ${R}_{\mathrm{skin}}^{208}=0.20{4}_{\ensuremath{-}0.026}^{+0.030}\text{ }\text{ }\mathrm{fm}$ by using the universal relation between ${R}_{\mathrm{skin}}^{208}$ and $L$. The bulk properties of canonical $1.4\text{ }\text{ }{M}_{\ensuremath{\bigodot}}$ NS (e.g., ${R}_{1.4}$ and ${\mathrm{\ensuremath{\Lambda}}}_{1.4}$) as well as the pressure (${P}_{2{\ensuremath{\rho}}_{\mathrm{sat}}}$) at two times the nuclear saturation density are well constrained by the data; i.e., ${R}_{1.4}$, ${\mathrm{\ensuremath{\Lambda}}}_{1.4}$, and ${P}_{2{\ensuremath{\rho}}_{\mathrm{sat}}}$ are approximately constrained to $12.3\ifmmode\pm\else\textpm\fi{}0.7\text{ }\text{ }\mathrm{km}$, ${330}_{\ensuremath{-}100}^{+140}$, and ${4.1}_{\ensuremath{-}1.2}^{+1.5}\ifmmode\times\else\texttimes\fi{}{10}^{34}\text{ }\text{ }\mathrm{dyn}\text{ }{\mathrm{cm}}^{\ensuremath{-}2}$, respectively. Besides, we find that the Bayes evidences of the hybrid star and normal NS assumptions are comparable, which indicates that current observation data are compatible with quarkyonic matter existing in the core of massive star. Finally, in the case of normal NS assumption, we obtain a constraint for the maximum mass of nonrotating NS ${M}_{\mathrm{TOV}}=2.3{0}_{\ensuremath{-}0.18}^{+0.30}\text{ }\text{ }{M}_{\ensuremath{\bigodot}}$. Based on this result and the current observational and theoretical knowledge about the NS population and its EOS, we find that a binary black hole merger scenario for GW190814 is more plausible. All of the uncertainties reported above are for 68.3% credible levels.