宇宙减速背景下物质扰动的演化
Evolution of matter perturbations in the context of cosmic slowing down
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中文总结 AI 辅助
该研究在爱因斯坦引力框架下分析五种暗能量参数化方案的物质扰动演化，通过增长指数等诊断量与ΛCDM模型对比，揭示动力学暗能量的现象学特征，为未来观测测试提供可观测量。
中文摘要 AI 辅助
我们通过分析物质扰动的演化，研究了爱因斯坦引力中具有 phantom 行为的动力学、随时间演化的暗能量模型。特别地，我们考虑了五种暗能量参数化方案，这些方案预测当前宇宙加速会减速。我们研究了增长指数及其一阶导数、组合参数以及 statefinder 诊断量的演化，并将它们的行为与标准 ΛCDM 模型进行了比较。在所考虑的参数选择下，当前的增长指数及其一阶导数的值与先前现象学研究报道的范围相符。还发现组合参数与其 ΛCDM 值存在差异，而 statefinder 参数提供了额外的手段，可用于区分所考虑的动力学暗能量场景与标准模型。我们的结果说明了与这些模型相关的现象学特征，并确定了可能对未来观测测试有用的可观测量。不过，我们强调，当前分析不构成统计模型比较，也未确立观测上偏好所考虑的任何动力学暗能量模型超过 ΛCDM。
英文摘要
We investigate dynamical, time-evolving dark-energy models exhibiting phantom behaviour within Einstein gravity by analysing the evolution of matter perturbations. In particular, we consider five dark-energy parameterisations that predict a slowing down of the current cosmic acceleration. We examine the evolution of the growth index and its first derivative, as well as the combination parameter and the statefinder diagnostics, and compare their behaviour with that of the concordance $Λ$CDM model. For the parameter choices considered, the present-day values of the growth index and its first derivative are found to be compatible with ranges reported in previous phenomenological studies. The combination parameter is also found to differ from its $Λ$CDM value, while the statefinder parameters provide additional means of distinguishing the considered dynamical dark-energy scenarios from the concordance model. Our results illustrate the phenomenological signatures associated with these models and identify observables that may be useful for future observational tests. We stress, however, that the present analysis does not constitute a statistical model comparison or establish an observational preference for any of the considered dynamical dark-energy models over $Λ$CDM.
