渐近de Sitter黑洞反弹时空的准正态模谱分析及其光学表现
Analyzing Quasi-normal modes spectrum in asymptotically de Sitter black bounces and their optical appearance
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中文总结 AI 辅助
本文研究渐近de Sitter黑洞反弹时空的正则性，采用伪谱方法计算其准正态模谱，结合光学观测特征，提出可通过观测区分该正则时空与奇异对应物的判别依据。
中文摘要 AI 辅助
本研究探讨渐近de Sitter黑洞反弹时空，该时空是通过Simpson-Visser方案对Schwarzschild-de Sitter几何的正则延拓。所得解族在单一几何框架内实现了正则黑洞、极端构型与可穿越虫洞之间的平滑插值。我们验证了该时空的正则性，表明曲率不变量（包括Kretschmann标量和Ricci标量）在正则化参数a取任意非零值时于原点保持有限，确保了测地完备性。对有效应力-能量张量的分析显示其违反零能量条件，这可被合理解释为包含phantom标量场与非线性电动力学耦合的复合源所致。随后，我们通过研究i)零测地线传播和ii)构建相关光学表现来探究这些几何的观测特征，具体通过数值光线追踪程序确定了阴影半径并表征光子环结构。最后，我们采用伪谱方法计算了轴向引力扰动谱，得到了准正态模频率及其泛音。结果表明，宇宙学常数与正则化标度a之间存在非平凡相互作用，这既体现在光子环结构上，也体现在准正态谱上。这些特征提示了潜在的观测判别依据，有望在未来的引力波观测和高分辨率电磁观测中，将这些正则时空与其奇异对应物区分开来。
英文摘要
This work explores asymptotically de Sitter black-bounce spacetimes, obtained as a regular extension of the Schwarzschild-de Sitter geometry via the Simpson-Visser prescription. The resulting family of solutions provides a smooth interpolation between regular black holes, extremal configurations, and traversable wormholes within a single geometrical framework. In particular, we verify the regularity of the spacetime by showing that (some of) curvature invariants, including the Kretschmann and Ricci scalars, remain finite at the origin for any non-vanishing value of the regularization parameter $a$, ensuring geodesic completeness. An analysis of the effective stress-energy tensor reveals a violation of the null energy condition, which can be consistently interpreted in terms of a composite source involving a phantom scalar field coupled to nonlinear electrodynamics. Subsequently, we investigate the observational signatures of these geometries by studying: i) null geodesic propagation and ii) constructing the associated optical appearance. In particular, we determine the shadow radius and characterize the structure of photon rings through numerical ray-tracing procedure. Finally, we compute the spectrum of axial gravitational perturbations using a pseudospectral approach, obtaining the quasinormal mode frequencies and their overtones. Our results show a non-trivial interplay between the cosmological constant and the regularization scale $a$, which imprints itself on both the light-ring structure and the quasinormal spectrum. These features suggest potential observational discriminants that could distinguish these regular spacetimes from their singular counterparts in future gravitational-wave and high-resolution electromagnetic observations.
