论文标题
积分中子星形地壳的热力学一致性状态方程
Thermodynamically consistent equation of state for an accreted neutron star crust
论文作者
论文摘要
我们研究积聚中子恒星外壳的状态方程（EOS）。通常，假设（隐式）认为内皮中的自由（未结合）中子和核一起移动。我们认为，此假设违反了$μ_n^\ infty = {\ rm const} $，这是未结合中子（$μ^\ infty_n $是红移中子化学势）的静水（和扩散）平衡所必需的。我们构建了一个尊重这种情况的新EO，在可压缩的液体差近似中起作用。我们证明，它在内部地壳的大部分地区都接近催化的EOS，这与文献中讨论的积聚地壳的eoss截然不同。特别是，外壳界面处的压力与通常在文献中计算的中子滴压压力不一致，并且由恒星内的静水（和扩散）平衡条件确定。我们还发现在完全吸收地壳的底部不稳定，将核转化为均匀的核物质。它可以保证，在积聚过程中，完全吸收地壳的结构保持自相似。
We study equation of state (EOS) of an accreting neutron star crust. Usually, such EOS is obtained assuming (implicitly) that the free (unbound) neutrons and nuclei in the inner crust move together. We argue, that this assumption violates the condition $μ_n^\infty={\rm const}$, required for hydrostatic (and diffusion) equilibrium of unbound neutrons ($μ^\infty_n$ is the redshifted neutron chemical potential). We construct a new EOS respecting this condition, working in the compressible liquid-drop approximation. We demonstrate that it is close to the catalyzed EOS in most part of the inner crust, being very different from EOSs of accreted crust discussed in the literature. In particular, the pressure at the outer-inner crust interface does not coincide with the neutron drip pressure, usually calculated in the literature, and is determined by hydrostatic (and diffusion) equilibrium conditions within the star. We also find an instability at the bottom of fully accreted crust that transforms nuclei into homogeneous nuclear matter. It guarantees that the structure of fully accreted crust remains self-similar during accretion.
