TY - JOUR

T1 - Constraints on the Dense Matter Equation of State and Neutron Star Properties from NICER’s Mass–Radius Estimate of PSR J0740+6620 and Multimessenger Observations

AU - Raaijmakers, G.

AU - Greif, S. K.

AU - Hebeler, K.

AU - Hinderer, T.

AU - Nissanke, S.

AU - Schwenk, A.

AU - Riley, T. E.

AU - Watts, A. L.

AU - Lattimer, J. M.

AU - Ho, W. C. G.

N1 - Publisher Copyright:
© 2021. The American Astronomical Society. All rights reserved.

PY - 2021/9/10

Y1 - 2021/9/10

N2 - In recent years our understanding of the dense matter equation of state (EOS) of neutron stars has significantly improved by analyzing multimessenger data from radio/X-ray pulsars, gravitational wave events, and from nuclear physics constraints. Here we study the additional impact on the EOS from the jointly estimated mass and radius of PSR J0740+6620, presented in Riley et al. by analyzing a combined data set from X-ray telescopes NICER and XMM-Newton. We employ two different high-density EOS parameterizations: a piecewise-polytropic (PP) model and a model based on the speed of sound in a neutron star (CS). At nuclear densities these are connected to microscopic calculations of neutron matter based on chiral effective field theory (EFT) interactions. In addition to the new NICER data for this heavy neutron star, we separately study constraints from the radio timing mass measurement of PSR J0740+6620, the gravitational wave events of binary neutron stars GW190425 and GW170817, and for the latter the associated kilonova AT2017gfo. By combining all these, and the NICER mass-radius estimate of PSR J0030+0451, we find the radius of a 1.4 M o˙ neutron star to be constrained to the 95% credible ranges 12.33-0.81+0.76 km (PP model) and 12.18-0.79+0.56km (CS model). In addition, we explore different chiral EFT calculations and show that the new NICER results provide tight constraints for the pressure of neutron star matter at around twice saturation density, which shows the power of these observations to constrain dense matter interactions at intermediate densities.

AB - In recent years our understanding of the dense matter equation of state (EOS) of neutron stars has significantly improved by analyzing multimessenger data from radio/X-ray pulsars, gravitational wave events, and from nuclear physics constraints. Here we study the additional impact on the EOS from the jointly estimated mass and radius of PSR J0740+6620, presented in Riley et al. by analyzing a combined data set from X-ray telescopes NICER and XMM-Newton. We employ two different high-density EOS parameterizations: a piecewise-polytropic (PP) model and a model based on the speed of sound in a neutron star (CS). At nuclear densities these are connected to microscopic calculations of neutron matter based on chiral effective field theory (EFT) interactions. In addition to the new NICER data for this heavy neutron star, we separately study constraints from the radio timing mass measurement of PSR J0740+6620, the gravitational wave events of binary neutron stars GW190425 and GW170817, and for the latter the associated kilonova AT2017gfo. By combining all these, and the NICER mass-radius estimate of PSR J0030+0451, we find the radius of a 1.4 M o˙ neutron star to be constrained to the 95% credible ranges 12.33-0.81+0.76 km (PP model) and 12.18-0.79+0.56km (CS model). In addition, we explore different chiral EFT calculations and show that the new NICER results provide tight constraints for the pressure of neutron star matter at around twice saturation density, which shows the power of these observations to constrain dense matter interactions at intermediate densities.

UR - https://www.mendeley.com/catalogue/b0c0d9db-ef6b-3650-8dc7-ee4ba434c5ae/

U2 - 10.3847/2041-8213/ac089a

DO - 10.3847/2041-8213/ac089a

M3 - Article

SN - 2041-8205

VL - 918

JO - Astrophysical Journal Letters

JF - Astrophysical Journal Letters

IS - 2

ER -