PSR J0030+0451, GW170817 and the nuclear data: joint constraints on equation of state and bulk properties of neutron stars

TL;DR

This study combines recent astrophysical observations and nuclear experiments to jointly constrain the equation of state and bulk properties of neutron stars, providing improved insights into their internal structure.

Contribution

It introduces a joint analysis method using NICER, GW170817, and nuclear data to refine neutron star property constraints, employing piecewise polytropic and spectral EoS parameterizations.

Findings

Pressure at twice nuclear saturation density measured as 3.38^{+2.43}_{-1.50}×10^{34} dyn cm^{-2}

Moment of inertia for 1.4 solar mass NS estimated as 1.43^{+0.28}_{-0.13}×10^{38} kg·m^2

Radius of 1.4 solar mass NS determined as 12.2^{+1.0}_{-0.9} km

Abstract

Very recently the NICER collaboration has published the first-ever accurate measurement of mass and radius together for PSR J0030+0451, a nearby isolated quickly-rotating neutron star (NS). In this work we set the joint constraints on the equation of state (EoS) and some bulk properties of NSs with the data of PSR J0030+0451, GW170817 and some nuclear experiments. The piecewise polytropic expansion method and the spectral decomposition method have been adopted to parameterize the EoS. The resulting constraints are consistent with each other. Assuming the maximal gravitational mass of non-rotating NS $M_{\rm TOV}$ lies between $2.04 \rm M_{\odot}$ and $2.4 \rm M_{\odot}$, with the piecewise method the pressure at twice nuclear saturation density is measured to be $3.38^{+2.43}_{-1.50}\times 10^{34}~{\rm dyn~cm^{-2}}$ at the $90\%$ level. For a NS with canonical mass of $1.4 \rm M_\odot$, we have the moment of inertia $I_{1.4} = {1.43}^{+0.28}_{-0.13} \times 10^{38}~{\rm kg \cdot m^2}$, tidal deformability $\Lambda_{1.4} = 390_{-140}^{+320}$, radius $R_{1.4} = 12.2_{-0.9}^{+1.0}~{\rm km}$, and binding energy $BE_{1.4} = {0.16}^{+0.01}_{-0.02} \rm M_{\odot}$ at the $90\%$ level, which are improved in comparison to the constraints with the sole data of GW170817.