早期暗能量是否吸收了DESI的晚时动力学信号？一项联合分析
Does Early Dark Energy Absorb the DESI Late-Time Dynamics Signal? A Combined Analysis
AI总结：
本研究结合EDE框架与CPL参数化分析发现，DESI的晚时DDE偏好是无法通过修改早期宇宙物理吸收的稳健信号，低红移DDE信号可由ΛCDM背景内的EDE成分解释。
AI中文摘要：
近期暗能量光谱仪（DESI）合作组的重子声学振荡（BAO）测量结果虽在很大程度上与平坦ΛCDM宇宙学模型相符，但所偏好的参数与宇宙微波背景（CMB）确定的参数存在轻微张力。DESI合作组提出了一种晚时动力学暗能量（DDE）解决方案以解决这一张力。本研究旨在探究对DDE的统计偏好是真实的晚时现象，还是未解决的早期宇宙物理的人为产物。为此，我们结合早期暗能量（EDE）框架与Chevallier-Polarski-Linder（CPL）参数化，同时允许对膨胀历史进行早期和晚时修改。排除DESI BAO测量值后，我们对CMB+Pantheon+数据集的联合分析表明，在EDE扩展框架内，CPL参数与标准ΛCDM模型在统计上一致。这支持了低红移处的DDE信号可由ΛCDM背景内的EDE成分有效解释的假设。然而，将DESI BAO测量值纳入联合分析后，出现了与宇宙学常数的统计显著偏差。在该联合框架内，最佳拟合CPL参数明确表明其偏离标准ΛCDM模型，倾向于暗能量状态方程从幻影到 Quintessence 的转变。这表明DESI对晚时DDE的偏好是一种无法通过修改早期宇宙物理来吸收的稳健信号。
英文摘要：
While the recent Baryon Acoustic Oscillation (BAO) measurements from the Dark Energy Spectroscopic Instrument (DESI) collaboration are largely consistent with a flat $Λ$CDM cosmology, the preferred parameters are in mild tension with those determined from the cosmic microwave background (CMB). A late-time dynamical dark energy (DDE) solution has been proposed by the DESI collaboration to address this tension. In this work, we investigate whether the statistical preference for DDE is a genuine late-time phenomenon or an artifact of unresolved early-universe physics. To do so, we simultaneously allow for both early- and late-time modifications to the expansion history by combining the Early Dark Energy (EDE) framework with the Chevallier-Polarski-Linder (CPL) parametrization. Excluding the DESI BAO measurements, our joint analysis of the CMB+Pantheon+ datasets demonstrates that within an EDE-extended framework, the CPL parameters remain statistically consistent with the standard $Λ$CDM model. This supports the hypothesis that a DDE signal at low redshifts can be effectively accounted for by an EDE component within the $Λ$CDM background. However, upon the inclusion of the DESI BAO measurements in the joint analysis, a statistically significant deviation from a cosmological constant emerges. Within this combined framework, the best-fit CPL parameters robustly indicate a departure from the standard $Λ$CDM model, favoring a phantom-to-quintessence transition in the DE equation of state. This demonstrates that the DESI preference for the late-time DDE is a robust signature that cannot be absorbed by modifying the physics of the early Universe.
