2021ApJ...921...63B

In this paper, we discuss the impact of the following laboratory experiments and astrophysical observation of neutron stars (NSs) on their equation of state (EoS): (a) the new measurement of neutron skin thickness of ²⁰⁸Pb, R_skin²⁰⁸=0.29±0.07 fm by the PREX-II experiment; (b) the mass measurement of PSR J0740+6620 has been slightly revised down by including additional ∼1.5 yr of pulsar timing data. As well as the radius measurement of PSR J0740+6620 by joint NICER/XMM-Newton collaboration, which has a similar size to PSR J0030+0451. We combine this information using Bayesian statistics along with the previous LIGO/Virgo and NICER observations of NS using a hybrid nuclear+piecewise-polytrope EoS parameterization. Our findings are as follows. (a). Adding PREX-II result yields the value of empirical parameter L=69_–19⁺²¹ MeV, R_skin²⁰⁸=0.20_–0.05^+0.05 fm, and radius of a 1.4 M_☉ (R_1.4)=12.75_–0.54^+0.42 km at 1σ confidence interval. We find these inferred values are mostly dominated by the combined astrophysical observations as the measurement uncertainty in R_skin²⁰⁸ by PREX-II is much broader. Also, a better measurement of R_skin²⁰⁸ might have a small effect on the radius of low-mass NSs but, for the high masses, there will be almost no effect. (b) After adding the revised mass and radius measurement of PSR J0740+6620, we find the inferred radii of NSs are slightly pushed toward the larger values and the uncertainty on the radius of a 2.08 M_☉ NS is moderately improved.