标题： 中子星在密近双星中的中心密度 显示英文标题

标题： The central density of neutron stars in close binaries

摘要： 最近由Wilson、Mathews和Marronetti（WMM）进行的合并双中子星的数值模拟显示，随着轨道分离度的减小，恒星的中心能量密度在上升，即当恒星接近合并时，它们各自被压碎。他们声称这种“恒星压碎”效应部分是由于另一颗恒星的存在导致每颗恒星自身引力的非线性、第一后牛顿阶增强。我们提供了一个具体的计算，结果显示，在广义相对论中，与另一颗恒星的第一后牛顿阶相互作用不会改变随着轨道半径减小的中心能量密度。这里呈现的结果与WMM的主张存在明显分歧。然而，其他引力理论，如Brans-Dicke理论，在双星成分接近合并时可以表现出轻微的压碎效应。我们表明，在第一后牛顿阶下缺乏恒星压碎效应与遵守强等效原理有关。 显示英文摘要

摘要： Recent numerical simulations of coalescing binary neutron stars conducted by Wilson, Mathews and Marronetti (WMM) show a rising central energy density of the stars as the orbital separation shrinks, i.e. the stars are individually crushed as they near coalescence. They claim this ``star-crushing'' effect is partially due to a non-linear, first post-Newtonian order enhancement of the self-gravity of each star caused by the presence of the other star. We present a concrete calculation which shows, within general relativity, first post-Newtonian order interactions with the other star leave the central energy density unchanged as the orbital radius shrinks. The results presented here are in sharp disagreement with the WMM claim. However, alternative gravitational theories, such as Brans-Dicke theory, can exhibit a small crushing effect in the binary constituents as they near coalescence. We show that the absence of the star-crushing effect at first post-Newtonian order is related to adherence to the strong equivalence principle.