发表机构
Korea Astronomy and Space Science Institute; University of Science and Technology（韩国天文学与宇宙学研究所; 科学技术大学）
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DESI DR2等数据检验标准宇宙学模型中暗物质$w=0$、暗能量$w=-1$的假设，发现两者均偏离标准值，且暗物质参数的偏差或导致对暗能量幻影穿越的误判。
AI 中文摘要
在标准宇宙学模型中，暗物质被假定为无压物质，其状态方程为$w=0$，暗能量的状态方程为$w=-1$。我们结合DESI DR2的距离测量数据对这些假设进行联合检验，其中包括最新的莱曼-阿尔法全形状阿尔科克-帕钦斯基（AP）信息、DES超新星以及两种互补的宇宙微波背景（CMB）处理方式。当同时变化常数$w_{dm}$（暗物质状态方程参数）和$w_{de}$（暗能量状态方程参数）时，我们得到$w_{dm}=0.000968^{+0.000501}_{-0.000496}$，$w_{de}=-0.9380^{+0.0259}_{-0.0262}$（68%置信区间）。采用另一种对引力透镜光谱进行边缘化处理的CMB方法时，对应的约束结果为$w_{dm}=0.000870^{+0.000408}_{-0.000410}$，$w_{de}=-0.9353^{+0.0258}_{-0.0254}$。在联合扩展模型中，两个标准$\boldsymbol{\rm \u039A CDM}$（Lambda-CDM）模型的参数值均被排斥在约$2\boldsymbol{\rm \u03C3}$置信水平之外；当仅单独变化某一参数时，该参数均未显著偏离其标准值。这种行为的产生源于晚宇宙距离测量倾向于$w_{de}>-1$，而要保持早期宇宙的物理物质密度则需要一个补偿性的正$w_{dm}$，这会改变其与当今物质密度的映射关系。允许暗能量动力学进一步阐明了该情形的复杂性：暗能量的幻影穿越行为使$w_{dm}=0$与数据一致，而当禁止幻影穿越时，正$w_{dm}$的偏好依然存在。值得注意的是，能够灵活描述一类 quintessence（精质）模型（无幻影穿越）的帕德-$w$参数化，结合自由的$w_{dm}$，在两种CMB处理方式下，根据最佳拟合$\boldsymbol{\rm \u03C7^2}$和DIC（偏差信息准则），甚至比幻影穿越$w_0w_a$模型更受青睐。我们可以得出结论：观测到的对幻影穿越的偏好可能反映的是暗物质 sector（部分）的偏差，而非仅暗能量的动力学特性。
英文摘要
In the standard model of cosmology, it is assumed that dark matter is pressureless with equation of state $w=0$ and dark energy has $w=-1$. We test these assumptions jointly using DESI DR2 distance measurements, including the recent Lyman-$α$ full-shape Alcock-Paczynski (AP) information, DES supernovae, and two complementary CMB treatment. When constant $w_{dm}$ and $w_{de}$ are varied together, we find $w_{dm}=0.000968^{+0.000501}_{-0.000496}$ and $w_{de}=-0.9380^{+0.0259}_{-0.0262}$ (68%). With an alternative CMB treatment that marginalizes over the lensing spectrum, the corresponding constraints are $w_{dm}=0.000870^{+0.000408}_{-0.000410}$ and $w_{de}=-0.9353^{+0.0258}_{-0.0254}$. Both standard $Λ$CDM values are disfavored at approximately $2σ$ in the joint extension. Neither parameter departs significantly from its standard value when only that parameter is varied. This behavior arises because late-time distances favor $w_{de}>-1$, while maintaining the early-Universe physical matter density requires a compensating positive $w_{dm}$, which changes the mapping to the matter density today. Allowing dynamical dark energy further highlights the complexity of the situation: phantom crossing for dark energy makes $w_{dm}=0$ consistent with the data, whereas a positive $w_{dm}$ preference persists when crossing is forbidden. Interestingly, the Pad'e-$w$ parameterization that provides a flexible description of a class of quintessence models (with no phantom crossing), along with $w_{dm}$ free, is even mildly favored over the phantom-crossing $w_0w_a$ model according to both the best-fit $χ^2$ and the DIC under both CMB treatments. One can conclude that the apparent preference for phantom crossing may instead reflect deviations in the dark-matter sector rather than dark-energy dynamics alone. [abridged]
Comments8+7 pages, 6 figures
Journal refAstrophys. J. Lett. 1010, L12 (2026)
