Constraint on phase transition with the multimessenger data of neutron stars

The equation of state (EoS) the neutron star (NS) matter remains an enigma. In this work we perform Bayesian parameter inference with gravitational wave data (GW170817) and mass-radius observations some NSs (PSR $\mathrm{J}0030+0451$, PSR $\mathrm{J}0437\ensuremath{-}4715$, 4U 1702-429) using phenomenologically constructed EoS models to search for a potential first-order phase transition. Our phenomenological take advantages current widely used parametrizing methods, which are flexible enough resemble various theoretical models. We find that observation still not informative support/rule out transition, due comparable evidences without However, bulk properties canonical $1.4\text{ }\text{ }{M}_{\ensuremath{\bigodot}}$ NS pressure at around $2{\ensuremath{\rho}}_{\mathrm{sat}}$ well constrained by data, where ${\ensuremath{\rho}}_{\mathrm{sat}}$ is nuclear saturation density. Moreover, strong transition low densities disfavored, $1\ensuremath{\sigma}$ lower bound density $1.84{\ensuremath{\rho}}_{\mathrm{sat}}$.