二次曲率-物质耦合引力中作为奇异星最大质量探针的引力波回声
Gravitational wave echoes as probes of the maximum mass of strange stars in quadratic curvature-matter coupled gravity
AI总结：
研究利用引力波天文学，在二次曲率引力与非最小物质耦合框架下，通过求解修正方程探讨奇异星产生引力波回声的可能性，得到质量-半径关系及相关限制，凸显奇异星作为回声源潜力，证明回声对修正引力等的探测作用。
AI中文摘要：
引力波天文学为高精度研究奇异致密星提供了范例途径。近期对GW170817的分析报告了可能的合并后引力波回声，显著性为4.2σ，主导频率近72Hz。此类回声可能源于具有部分捕获引力扰动的光子球的超致密遗迹。在广义相对论中，光子球形成要求恒星致密性在三分之一到九分之四之间，这对现实状态方程也颇具挑战。本文在二次曲率引力与非最小物质耦合中探讨此可能性，考虑MIT袋模型状态方程描述的奇异星。通过求解修正的托尔曼-奥本海默-沃尔科夫方程，得到质量-半径关系并确定能支持光子球和引力波回声的构型。在所提框架中，修正的布赫达赫尔极限允许更致密恒星解，而光子球约束限制了可行参数空间。发现增大袋常数会降低最大质量和回声时间，使回声频率移向kHz regime。回声约束给出比流体静力学平衡更严格的最大质量-半径限制，暗示奇异星最大质量界限的修正。这些结果凸显合并后奇异星作为引力波回声源的潜力，并证明回声作为修正引力和高频引力波探针的作用。
英文摘要：
Gravitational wave astronomy provides an exemplary avenue to study exotic compact stars with utmost precision. Recent analyses of GW170817 have reported possible post-merger gravitational wave echoes with a significance of $4.2σ$ and a dominant frequency near $72$ Hz. Such echoes may originate from ultracompact remnants possessing photon spheres that partially trap gravitational perturbations. In general relativity, photon-sphere formation requires the stellar compactness to lie within one-third and four-ninths, which is challenging even for a realistic equations of state. Here, we explore this possibility in quadratic curvature gravity with non-minimal matter coupling, considering strange stars described by the MIT bag model equation of state. By solving the modified Tolman-Oppenheimer-Volkoff equations, we obtain the mass-radius relations and identify configurations capable of supporting photon spheres and GW echoes. In the proposed framework, the modified Buchdahl limit allows more compact stellar solutions, while photon-sphere constraints restrict the viable parameter space. We find that increasing the bag constant, decreases the maximum mass and echo time, shifting the echo frequency toward the kHz regime. The echo constraints yield more stringent maximum mass-radius limits than hydrostatic equilibrium, suggesting a revised maximum mass bounds for strange stars. These results highlight the potential of post-merger strange stars as GW echo sources and demonstrate the role of echoes as probes of modified gravity and high-frequency gravitational waves.
