Constraints on the phase transition and nuclear symmetry parameters from PSR <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:mi mathvariant="normal">J</mml:mi><mml:mn>0740</mml:mn><mml:mo>+</mml:mo><mml:mn>6620</mml:mn></mml:mrow></mml:math> 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 skin thickness $^{208}\mathrm{Pb}$ (${R}_{\mathrm{skin}}^{208}$) reported PREX-II experiment. These new measurements can help us better understand unknown equation state (EOS) dense matter. In this work, we adopt a hybrid parameterization method, which incorporates nuclear empirical some widely used phenomenological parameterizations, to analyze results experiments astrophysical observations. With joint Bayesian analysis GW170817, $\mathrm{J}0030+0451$, $\mathrm{J}0740+6620$, parameters that characterize ultradense matter EOS are constrained. We find slope parameter $L$ is approximately constrained ${70}_{\ensuremath{-}18}^{+21}\text{ }\text{ }\mathrm{MeV}$, predicts ${R}_{\mathrm{skin}}^{208}=0.20{4}_{\ensuremath{-}0.026}^{+0.030}\text{ }\mathrm{fm}$ using universal relation between ${R}_{\mathrm{skin}}^{208}$ $L$. The bulk properties canonical $1.4\text{ }{M}_{\ensuremath{\bigodot}}$ NS (e.g., ${R}_{1.4}$ ${\mathrm{\ensuremath{\Lambda}}}_{1.4}$) as well pressure (${P}_{2{\ensuremath{\rho}}_{\mathrm{sat}}}$) at two times saturation density data; i.e., ${R}_{1.4}$, ${\mathrm{\ensuremath{\Lambda}}}_{1.4}$, ${P}_{2{\ensuremath{\rho}}_{\mathrm{sat}}}$ $12.3\ifmmode\pm\else\textpm\fi{}0.7\text{ }\mathrm{km}$, ${330}_{\ensuremath{-}100}^{+140}$, ${4.1}_{\ensuremath{-}1.2}^{+1.5}\ifmmode\times\else\texttimes\fi{}{10}^{34}\text{ }\mathrm{dyn}\text{ }{\mathrm{cm}}^{\ensuremath{-}2}$, respectively. Besides, Bayes evidences normal assumptions comparable, indicates current observation data compatible with quarkyonic existing in core massive star. Finally, case assumption, obtain constraint for maximum mass nonrotating ${M}_{\mathrm{TOV}}=2.3{0}_{\ensuremath{-}0.18}^{+0.30}\text{ }{M}_{\ensuremath{\bigodot}}$. Based on result observational theoretical knowledge about population its EOS, binary black hole merger scenario GW190814 more plausible. All uncertainties above 68.3% credible levels.