发表机构
Hunan Normal University（湖南师范大学）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
该研究结合多组观测数据，评估暗 sector 相互作用与动力学暗能量的简并性，发现不同暗能量轨迹下相互作用的表现差异显著，晚时大尺度结构观测或可区分二者。
AI 中文摘要
来自DESI数据发布2（DESI DR2）的近期重子声学振荡测量结果，结合宇宙微波背景（CMB）与超新星数据，增强了探索晚时膨胀历史偏离ΛCDM模型的动机。由于演化的暗能量状态方程和暗 sector 内的相互作用会对背景膨胀产生部分简并效应，因此应同时评估它们的观测信号。我们首先考虑带有Q=βHρ_de的相互作用w0waCDM模型，使用普朗克（Planck）和ACT的CMB数据、DESI DR2以及DES-Dovekie超新星数据。允许暗能量状态方程大幅演化会显著降低对非零耦合的偏好，而对动力学暗能量的偏好依然存在。该相互作用在最佳拟合中几乎没有提供额外改善，表明在约束更严格的相互作用模型中发现的部分耦合偏好可能反映了与暗能量动力学的简并性。随后，我们针对三种单参数动力学暗能量轨迹（解冻轨迹、幻影轨迹、广义涌现暗能量（GEDE））研究了相同的相互作用。相互作用的作用高度依赖于所假设的轨迹：解冻模型和GEDE模型倾向于大小相当但符号相反的耦合，而幻影轨迹已非常接近数据偏好的暗能量演化，几乎不支持额外的相互作用。这些模型在结构增长方面也预测出明显不同的信号，从相互作用解冻模型中增强的物质成团到相互作用GEDE模型中强烈的抑制。尽管在背景层面存在显著简并，但这些对比的增长信号凸显了晚时大尺度结构观测是区分暗能量动力学与暗 sector 相互作用的有前景途径。
英文摘要
Recent baryon acoustic oscillation measurements from DESI Data Release 2, when combined with CMB and supernova data, strengthen the motivation for exploring departures from $Λ$CDM in the late-time expansion history. Because an evolving dark-energy equation of state and an interaction within the dark sector can produce partially degenerate effects on the background expansion, their observational signatures should be assessed simultaneously. We first consider an interacting $w_0w_a$CDM model with $Q=βHρ_{\rm de}$, using Planck and ACT CMB data, DESI DR2, and DES-Dovekie supernovae. Allowing the dark-energy equation of state to evolve substantially weakens the preference for a nonzero coupling, while the preference for dynamical dark energy persists. The interaction provides essentially no additional improvement in the best fit, suggesting that part of the coupling preference found in more restricted interacting models may reflect a degeneracy with dark-energy dynamics. We then examine the same interaction for three one-parameter dynamical dark-energy trajectories: thawing, mirage, and generalized emergent dark energy (GEDE). The role of the interaction depends strongly on the assumed trajectory. The thawing and GEDE models favor sizable couplings of opposite signs, whereas the mirage trajectory already closely follows the dark-energy evolution preferred by the data and provides little support for an additional interaction. These models also predict markedly different signatures in structure growth, ranging from enhanced matter clustering in the interacting thawing model to strong suppression in interacting GEDE. These contrasting growth signatures, despite substantial degeneracies at the background level, highlight late-time large-scale-structure observations as a promising avenue for distinguishing dark-energy dynamics from dark-sector interactions.
