中子星作为完美流体：提取线性化响应函数
Neutron Stars as Perfect Fluids: Extracting the Linearized Response Function
AI总结：
提出有效场论框架，通过线性化协变流体作用量并匹配世界线理论，解析计算中子星保守线性潮汐响应中的模态动力学潮汐形变率，并识别非极点贡献。
摘要：
我们为相对论性中子星（建模为具有守恒粒子数的完美流体）的保守线性潮汐响应开发了一个有效场论框架。从弯曲背景下的协变流体作用量出发，我们线性化静态平衡构型，得到流体位移与度规扰动耦合的二次作用量。然后将度规扰动分为诱导部分和外部源部分，并使用对称格林函数在保守匹配域上积分出诱导度规。得到的有效流体理论包含通过作用于位移的自伴算子的度规介导的流体相互作用，而外部扰动作为潮汐源。这种自伴结构允许极点部分的模态展开：投影到保守本征模后，动力学简化为由潮汐驱动的振荡器，其耦合由相对论内积和重叠积分确定。将这些振荡器变量与四极世界线理论匹配，给出了模态动力学潮汐形变率的解析表达式，用模态频率、归一化和重叠积分表示。我们还识别了一个仅由外部扰动二次项产生的源非极点部分。该部分不影响模态振幅，但其电四极投影可以对完整潮汐响应有贡献。这一公式阐明了相对论潮汐响应的哪一部分由显式流体模态捕获，以及可能的仅源非极点贡献在何处进入世界线描述。
英文摘要：
We develop an effective field theory framework for the conservative linear tidal response of a relativistic neutron star modeled as a perfect fluid with conserved particle number. Starting from the covariant fluid action in a curved background, we linearize about a static equilibrium configuration and obtain the quadratic action for fluid displacements coupled to metric perturbations. We then split the metric perturbation into induced and externally sourced parts, and integrate out the induced metric on a conservative matched domain using a symmetric Green kernel. The resulting effective fluid theory contains metric-mediated fluid interactions through a self-adjoint operator acting on the displacement, while the external perturbation acts as a tidal source. This self-adjoint structure permits a modal expansion of the pole sector: after projection onto conservative eigenmodes, the dynamics reduce to tidally driven oscillators with couplings fixed by relativistic inner products and overlap integrals. Matching these oscillator variables to the quadrupolar worldline theory gives analytic expressions for the modal dynamical tidal deformabilities in terms of mode frequencies, normalizations, and overlap integrals. We also identify a source-only non-pole sector generated by terms quadratic in the external perturbation. This sector does not affect the mode amplitudes, but its electric-quadrupolar projection can contribute to the full tidal response. This formulation clarifies which part of the relativistic tidal response is captured by explicit fluid modes and where a possible source-only non-pole contribution enters the worldline description.
机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。
