AI 中文总结
研究扩展Cuscuton模型的非动力学暗能量，用当前探针约束其四个基准子模型，预测第三代标准汽笛能大幅提升约束精度，为超越ΛCDM的暗能量提供互补检验。
AI 中文摘要
我们研究了扩展Cuscuton模型的一个解析易处理分支，该模型是可行Horndeski引力框架内的一种非动力学暗能量实现。我们聚焦四个基准子模型，利用当前背景探针（即宇宙计时器、Ia型超新星和重子声学振荡（BAO））对其进行约束，同时施加理论可行性、月球激光测距和大爆炸核合成的限制条件。随后，我们结合爱因斯坦望远镜（Einstein Telescope）和宇宙探测器（Cosmic Explorer）网络，预测第三代明亮标准汽笛的约束能力，考虑了瞬发辐射、余辉和千新星对应体。当前数据已将可行参数空间限制为与ΛCDM模型的微小偏离，且未消除CC+SN与CC+BAO对哈勃常数H₀测定之间由校准导致的偏移。原则上，未来明亮汽笛将大幅提升约束精度，尤其是千新星星表与扩展探测器网络的情况。在所有预测配置中，H₀的相对不确定性均低于13.18%，在约束最强的情况下可达0.21%；而在最优情况下，宇宙学常数密度Ω_Λ的恢复精度可达百分位级别。这些结果表明，第三代标准汽笛可对超越ΛCDM的非动力学暗能量提供精确的互补性检验。
英文摘要
We investigate an analytically tractable sector of the Extended Cuscuton model, a non-dynamical dark-energy realization within the framework of viable Horndeski gravity. We focus on four benchmark submodels and constrain them with current background probes, namely cosmic chronometers, Type-Ia supernovae, and BAO, while imposing theoretical viability, Lunar Laser Ranging, and Big Bang Nucleosynthesis bounds. We then forecast third-generation bright-standard-siren constraints with Einstein Telescope and Cosmic Explorer networks, considering prompt-emission, afterglow, and kilonova counterparts. Current data already restrict the viable parameter space to small departures from $Λ$CDM and do not remove the calibration-driven offset between the CC+SN and CC+BAO determinations of $H_0$. In principle, future bright sirens substantially sharpen the constraints, especially for kilonova catalogues and extended detector networks. Across the forecast configurations, the relative uncertainty on $H_0$ remains below $13.18\%$ and can reach $0.21\%$ in the most constraining cases, while $Ω_Λ$ is recovered at the percent level in the best cases. These results show that third-generation standard sirens can provide a precise complementary test of non-dynamical dark energy beyond $Λ$CDM.
Comments23 pages, 19 figures, 2 tables
