Direct astrophysical tests of chiral effective field theory at supranuclear densities
Direct astrophysical tests of chiral effective field theory at supranuclear densities
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DOI：
10.1103/physrevc.102.055803
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发表时间：
2020-04
影响因子：
3.1
通讯作者：
R. Essick;I. Tews;P. Landry;S. Reddy;D. Holz
中科院分区：
文献类型：
--
作者：
R. Essick;I. Tews;P. Landry;S. Reddy;D. Holz
最近对具有引力波和X射线计时的中子星的观测提供了前所未有的途径，可以获得密度在地面实验中难以实现的冷致密物质的状态方程(Eos)。同时，用手征有效场论的可靠不确定度估计对状态方程的预测，也限制了我们理论上的无知。在这项工作中，我们使用中子星状态方程的非参数表示来分析天体物理数据，以直接约束致密天体的基本物理性质。我们讨论了当我们以低密度下的EFT为条件时，数据本身是如何约束高密度下的状态方程的。我们还演示了如何利用天体物理数据来直接检验EOS的两倍核饱和密度的预测，并估计这些预测可能失败的密度。我们发现，大质量脉冲星的存在，GW170817引力波的存在，以及PSR J0030+0451更好的观测，都有利于EFT对Eos直到核饱和密度的预测，而不是本工作中使用的量子蒙特卡罗(QMC)计算的7倍的不可知性分析。虽然使用QMC的EFT预测与引力波数据完全一致，但更好的观测表明，在核饱和密度下，EOS相对于这些预测是坚硬的。此外，我们忽略了$\chi$EFT开始分解的密度的不确定性，从而限制了$1.4的半径，中子星M_(1.4)=11.40^R_(+1.38)_(-1.04)$($12.54^{+0.71}_(-0.63)}$p(2n_\mathm{sat})=14.2^{+18.1}_(-8.4)$($28.7^{+15.3}__(-15.0)})$\mathm{MeV}/\mathm{fm}^3$。
Recent observations of neutron stars with gravitational waves and X-ray timing provide unprecedented access to the equation of state (EoS) of cold dense matter at densities difficult to realize in terrestrial experiments. At the same time, predictions for the EoS with reliable uncertainty estimates from chiral effective field theory ($\chi$EFT) bound our theoretical ignorance. In this work, we analyze astrophysical data using a nonparametric representation of the neutron star EoS conditioned on $\chi$EFT to directly constrain the underlying physical properties of the compact objects. We discuss how the data alone constrain the EoS at high densities when we condition on $\chi$EFT at low densities. We also demonstrate how to exploit astrophysical data to directly test the predictions of $\chi$EFT for the EoS up to twice nuclear saturation density, and estimate the density at which these predictions might break down. We find that the existence of massive pulsars, gravitational waves from GW170817, and NICER observations of PSR J0030+0451 favor $\chi$EFT predictions for the EoS up to nuclear saturation density over a more agnostic analysis by a factor of 7 for the quantum Monte Carlo (QMC) calculations used in this work. While $\chi$EFT predictions using QMC are fully consistent with gravitational-wave data up to twice nuclear saturation, NICER observations suggest that the EoS stiffens relative to these predictions at nuclear saturation density. Additionally, we marginalize over the uncertainty in the density at which $\chi$EFT begins to break down, constraining the radius of a $1.4\,M_\odot$ neutron star to $R_{1.4} = 11.40^{+1.38}_{-1.04}$ ($12.54^{+0.71}_{-0.63}$) km and the pressure at twice nuclear saturation density to $p(2n_\mathrm{sat}) = 14.2^{+18.1}_{-8.4}$ ($28.7^{+15.3}_{-15.0}$) $\mathrm{MeV}/\mathrm{fm}^3$ with massive pulsar and gravitational-wave (and NICER) data.