比较质量变化中微子暗能量模型与DESI DR2：宇宙学约束与贝叶斯证据
Comparing Mass-Varying Neutrino Dark Energy Models with DESI DR2: Cosmological Constraints and Bayesian Evidence
- Lovely Professional University（洛维专业大学）
- Lorestan University（洛雷斯坦大学）
- Khazar University（哈萨尔大学）
- Amity University Uttar Pradesh（阿米蒂北方邦大学）
机构由 AI 辅助整理，请以论文原文为准。
中文总结 AI 辅助
本研究比较三种质量变化中微子暗能量模型，结合DESI DR2等数据，发现非零耦合与数据一致，但贝叶斯证据未明确支持，结果仅具提示性。
中文摘要 AI 辅助
我们研究了质量变化中微子（MaVaN）暗能量情景中的晚期宇宙加速，其中中微子质量通过共形相互作用与动力学精质场耦合。从耦合守恒方程出发，我们推导了三种相关情景对应的背景演化方程：具有恒定耦合的恒定暗能量状态方程（情形I）、在绝热最小跟踪近似下与指数势相关的指数中微子质量（情形II）、以及具有恒定耦合的CPL型时变状态方程（情形III）。对于每种情形，我们获得了中微子和暗能量的密度演化以及相应的哈勃参数，并使用MCMC分析（emcee）将模型与DESI DR2 BAO数据、压缩的普朗克CMB似然以及三个超新星汇编（Pantheon+、DES-SN5YR、Union3）逐一进行测试。在三种情形中，$H_0$和$\Omega_{m0}$以主要由所使用的超新星样本决定的方式共同移动，遵循其他DESI DR2分析中已见的模式。非零耦合在大多数拟合中与数据保持一致，尽管其大小（有时是符号）取决于其进入模型的方式以及为底层参数选择的先验。所得中微子质量界限范围约为$0.06$至$0.3\\,\mathrm{eV}$，具体取决于情形和数据集组合。将每种情形的贝叶斯证据与平坦$\Lambda$CDM进行比较，结果呈现混合图景，没有一种情形在所有情况下都被优先选择，因此我们认为这些结果提示性而非确凿证据，表明中微子与暗能量之间存在耦合。
英文摘要
We investigate late-time cosmic acceleration in mass-varying neutrino (MaVaN) dark energy scenarios, where the neutrino mass is coupled to a dynamical quintessence field through a conformal interaction. Starting from the coupled conservation equations, we derive the corresponding background evolution equations for three related scenarios: a constant dark-energy equation of state with a constant coupling (Case-I), an exponential neutrino mass linked to an exponential potential under an adiabatic minimum-tracking approximation (Case-II), and a CPL-type time-varying equation of state with constant coupling (Case-III). For each case we obtain the neutrino and dark energy density evolution and the corresponding Hubble parameter, and use an MCMC analysis (emcee) to test the models against DESI DR2 BAO data, the compressed Planck CMB likelihood, and three supernova compilations (Pantheon+, DES-SN5YR, Union3), taken one at a time. Across the three cases, $H_0$ and $Ω_{m0}$ move together in a way set mainly by which supernova sample is used, following the pattern already seen in other DESI DR2 analyses. A nonzero coupling stays consistent with the data in most fits, though its size, and sometimes its sign, depend on how it enters the model and on the priors chosen for the underlying parameters. The resulting neutrino mass bounds range from about $0.06$ to $0.3\,\mathrm{eV}$, depending on the case and dataset combination. Comparing the Bayesian evidence of each case with flat $Λ$CDM gives a mixed picture, with no case preferred throughout, so we regard these results as suggestive rather than firm evidence for a coupling between neutrinos and dark energy.
