论文标题
中子星中声速的一般，与规模无关的描述
A general, scale-independent description of the sound speed in neutron stars
论文作者
论文摘要
使用满足理论和观察性约束的一百万个随机生成的状态方程，我们构建了对中子恒星中声速的新颖的，无关紧要的描述，其中后者在跨越标准化半径，$ r/r $的单位立机中表达，$ r/r $，质量归一部分为$ m/m _ _ _ _ {\ rm rm tov} $。从这种通用表示，可以推导出许多有趣且令人惊讶的结果。特别是，我们发现光（重）恒星分别具有刚性（柔软的）芯和柔软（刚性）外层，或者声音速度的最大值位于光星的中心，但移动到具有$ m/m _ {\ rm的星星的外层。 tov} \ gtrsim0.7 $，达到$ c_s^2 = 1/2 $的常数值为$ m \ to m _ {\ rm tov} $。我们还表明，在星星中心，$ m = m _ {\ rm的星星中心的声速降低以下$ c_s^2 = 1/3 $ tov} $。最后，我们构建了一个分析表达式，该分析表达能够准确地描述声速作为中子星质量的函数的径向依赖性，从而提供了中子星中预期的最大声速的估计。
Using more than a million randomly generated equations of state that satisfy theoretical and observational constraints we construct a novel, scale-independent description of the sound speed in neutron stars where the latter is expressed in a unit-cube spanning the normalised radius, $r/R$, and the mass normalized to the maximum one, $M/M_{\rm TOV}$. From this generic representation, a number of interesting and surprising results can be deduced. In particular, we find that light (heavy) stars have stiff (soft) cores and soft (stiff) outer layers, respectively, or that the maximum of the sound speed is located at the center of light stars but moves to the outer layers for stars with $M/M_{\rm TOV}\gtrsim0.7$, reaching a constant value of $c_s^2=1/2$ as $M\to M_{\rm TOV}$. We also show that the sound speed decreases below the conformal limit $c_s^2=1/3$ at the center of stars with $M=M_{\rm TOV}$. Finally, we construct an analytic expression that accurately describes the radial dependence of the sound speed as a function of the neutron-star mass, thus providing an estimate of the maximum sound speed expected in a neutron star.
