自作用力作为引力星内部的非局域探针
Self-Forces as Nonlocal Probes of Gravastar Interiors
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中文总结 AI 辅助
该研究计算了薄壳引力星中标量荷与电荷的静态保守自作用力，发现其与同质量史瓦西黑洞不同，证明自作用力可作为探测引力星内部全局结构的非局域探针。
中文摘要 AI 辅助
具有相同外部度规的致密天体对检验粒子而言在局域上不可区分，但由推迟场构建的可观测量可保留粒子紧邻邻域外的时空信息。弯曲时空中粒子受到的自作用力为背景时空的局域几何与全局结构提供了独特探针。我们计算了最简薄壳引力星中，极小耦合标量荷与电荷受到的静态保守自作用力：该引力星为德西特核与史瓦西外部的匹配结构。我们在致密性参数M/R下得到了弱场展开并以闭合形式求和。对于引力星外的标量荷，其自作用力非零——这与相同质量史瓦西黑洞的严格消失结果形成对比——且在远距离处表现为(2/5)q²MR²/r₀⁵；而对于电荷，普适的史密斯-威尔力e²M/r₀³会被一个结构相关项(4/5)e²MR²/r₀⁵修正。在引力星内部，标量自作用力在M/R的主导阶指向中心，在中心处线性消失，会使电荷围绕中心产生简谐振荡；引力星内部的电磁自作用力表现类似。这些结果明确证明，自作用力不仅依赖于粒子周围的局域曲率，还依赖于时空的全局结构：尽管引力星的外部几何与史瓦西黑洞完全相同，但其内部边界条件会修改正则场，从而产生不同的自作用力。
英文摘要
Compact objects with the same exterior metric are locally indistinguishable to test particles, yet observables built from retarded fields can retain information about the spacetime outside the particle's immediate neighbourhood. The self-force acting on a particle in curved spacetime provides a unique probe of both the local geometry and the global structure of the background spacetime. We calculate the static, conservative self-force on minimally coupled scalar and electric charges in the simplest thin-shell gravastar: a de Sitter core matched to a Schwarzschild exterior. Weak-field expansions in the compactness $M/R$ are obtained analytically and summed in closed form. For a scalar charge outside the gravastar the self-force is nonzero---in contrast to the exactly vanishing result for a Schwarzschild black hole of the same mass---and behaves as $\tfrac{2}{5}q^2 M R^2/r_0^5$ at large distances, while for an electric charge the universal Smith--Will force $e^2M/r_0^3$ is corrected by a structure-dependent term $\tfrac{4}{5}e^2 M R^2/r_0^5$. Inside the gravastar the scalar self-force is directed toward the center at leading order in $M/R$, vanishes linearly at the center, and produces harmonic oscillations of the charge about the center; the electromagnetic self-force inside the gravastar behaves similarly. The results demonstrate explicitly that the self-force depends not only on the local curvature surrounding the particle but also on the global structure of spacetime: although the exterior geometry of a gravastar is identical to that of a Schwarzschild black hole, the interior boundary conditions modify the regular field and therefore produce distinct self-forces.
