论文标题
关于中子星的音速
On the Sound Speed in Neutron Stars
论文作者
论文摘要
确定紧凑型恒星中的声速$ C_S $是一个重要的开放问题，对大密度的物质行为有许多影响，因此对中子星的重力波排放发射。在此范围内，我们以连续的音速构建了超过$ 10^7 $方程式（EOSS），并构建超过$ 10^8 $的非旋转恒星模型不仅与核理论和扰动QCD保持一致，而且还与天文学观察一致。通过这种方式，我们发现具有子符号音速的EOSS，即在星星中使用$ C^2_s <1/3 $，在原则上是可能的，但在实践中不太可能，仅是$ 0.03 \％\％\％。因此，很自然地期望$ c^2_s> 1/3 $在恒星内部的某个地方。使用我们的大型样本，我们获得的估计值为$ 95 \％$ $ $ $ $ $ $ r_ {1.4} = 12.42^{+0.52} _ { - 0.99}} $ r_ {2.0} = 12.12^{+1.11} _ { - 1.23} \，{\ rm km km} $，对于GW170817事件的二进制潮汐变形，$ \tildeλ__有趣的是，我们在半径上的较低距离与从截然不同的论点（即阈值质量）得出的预测非常吻合。最后，我们提供简单的分析表达式，以确定$ \tildeλ$的最小值和最大值作为CHIRP质量的函数。
Determining the sound speed $c_s$ in compact stars is an important open question with numerous implications on the behaviour of matter at large densities and hence on gravitational-wave emission from neutron stars. To this scope, we construct more than $10^7$ equations of state (EOSs) with continuous sound speed and build more than $10^8$ nonrotating stellar models consistent not only with nuclear theory and perturbative QCD, but also with astronomical observations. In this way, we find that EOSs with sub-conformal sound speeds, i.e. with $c^2_s < 1/3$ within the stars, are possible in principle but very unlikely in practice, being only $0.03\%$ of our sample. Hence, it is natural to expect that $c^2_s > 1/3$ somewhere in the stellar interior. Using our large sample, we obtain estimates at $95\%$ credibility of neutron-star radii for representative stars with $1.4$ and $2.0$ solar masses, $R_{1.4}=12.42^{+0.52}_{-0.99}\,{\rm km}$, $R_{2.0}=12.12^{+1.11}_{-1.23}\,{\rm km}$, and for the binary tidal deformability of the GW170817 event, $\tildeΛ_{1.186}=485^{+225}_{-211}$. Interestingly, our lower-bounds on the radii are in very good agreement with the prediction derived from very different arguments, namely, the threshold mass. Finally, we provide simple analytic expressions to determine the minimum and maximum values of $\tildeΛ$ as a function of the chirp mass.
