用修正涌现暗能量探测非冷暗物质
Probing Non-Cold Dark Matter with Modified Emergent Dark Energy
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中文总结 AI 辅助
本研究在修正涌现暗能量框架中引入自由暗物质状态方程参数，利用CMB、BAO和超新星数据约束模型，发现2.6σ-3σ水平的非零w_dm偏好，但尚未构成稳健探测。
中文摘要 AI 辅助
在标准ΛCDM宇宙学中，暗物质被假定为一种无压冷流体，其状态方程参数w_dm=0。然而，暗物质的微观本质仍然未知，其状态方程参数是否严格为零值得观测检验。在本工作中，我们在修正涌现暗能量（MEDE）框架内引入一个自由的暗物质状态方程参数w_dm，构建了MEDE+w_dm模型。我们系统地推导了其背景演化和线性扰动方程，并使用普朗克2018宇宙微波背景（CMB）、DESI DR2重子声学振荡（BAO）以及三个独立的Ia型超新星数据集：Pantheon+、Union3和DES5YR，对模型参数进行了约束。利用CMB+BAO+DES5YR组合，我们发现暗物质状态方程为正的偏好，w_dm=0.00128±0.00044，同时存在3σ水平的类精质暗能量演化偏好，α=-0.66±0.22。当加入本地H_0先验时，对w_dm的约束基本不变，而α则向ΛCDM极限移动，得到α=-0.18±0.18。贝叶斯模型比较倾向于ΛCDM优于MEDE+w_dm，尽管在加入本地H_0先验后，这种偏好减弱到较弱水平。总体而言，当前观测在参数后验水平上表现出2.6σ至3σ的偏好，支持非零的w_dm，但这一迹象尚不构成对非冷暗物质的稳健探测。
英文摘要
In the standard $Λ$CDM cosmology, dark matter is assumed to be a pressureless cold fluid with $w_{\rm dm}=0$. However, the microscopic nature of dark matter remains unknown, and whether its equation-of-state parameter strictly vanishes deserves observational scrutiny. In this work, we introduce a free dark matter equation-of-state parameter $w_{\rm dm}$ within the Modified Emergent Dark Energy (MEDE) framework, constructing the MEDE+$w_{\rm dm}$ model. We systematically derive its background evolution and linear perturbation equations, and constrain the model parameters using Planck 2018 cosmic microwave background (CMB), DESI DR2 baryon acoustic oscillation (BAO), and three independent Type Ia supernova datasets: Pantheon+, Union3, and DES5YR. Using the CMB + BAO + DES5YR combination, we find a preference for a positive dark matter equation of state, $w_{\rm dm}=0.00128\pm0.00044$, together with a 3$σ$ level preference for quintessence-like dark energy evolution, $α=-0.66\pm0.22$. When the local $H_0$ prior is included, the constraint on $w_{\rm dm}$ remains essentially unchanged, whereas $α$ shifts toward the $Λ$CDM limit, yielding $α=-0.18\pm0.18$. Bayesian model comparison favors $Λ$CDM over MEDE+$w_{\rm dm}$, although the preference is reduced to the weak level after including the local $H_0$ prior. Overall, current observations exhibit a $2.6σ$--$3σ$ preference for a nonzero $w_{\rm dm}$ at the parameter-posterior level, but this indication does not yet constitute a robust detection of non-cold dark matter.
发表机构
- Longyan University（龙岩学院）
- Ningbo University（宁波大学）
机构由 AI 辅助整理，请以论文原文为准。
