发表机构
University of Queensland; University of Wisconsin Madison; University of Hawai‘i at Mānoa; University College London（昆士兰大学; 威斯康星大学麦迪逊分校; 夏威夷大学马诺阿分校; 伦敦大学学院）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本研究将Pantheon+与DES-SN5YR超新星样本联合为Unite，构建了更全面的SN Ia数据集，结合多类宇宙学数据得到了暗能量随时间演化的约束，缓解了数据间的张力并提升了约束精度。
AI 中文摘要
我们展示了结合Pantheon+与DES-SN5YR超新星（SN）样本得到的哈勃图和宇宙学约束，将该联合样本命名为Unite。Unite对Pantheon+进行了更新，包含了DES样本所支持的方法学改进，并加入了DES巡天的新超新星，构成了目前最全面、内部一致性最高的Ia型超新星（SN Ia）数据集，共包含2884颗候选Ia型超新星。本研究采用了一致的SN Ia建模、样本选择和偏差校正方法，还利用统一框架重新确定了超过98%样本的宿主星系恒星质量。仅使用Unite样本，针对具有宇宙学常数的平坦宇宙（Flat-$\rm{\u039A}$CDM），我们得到$\rm{\u03A9_m = 0.310^{+0.012}_{-0.011}}$。我们进一步展示了将Unite样本与宇宙微波背景（CMB）数据、DES和DESI重子声学振荡（BAO）数据结合后的约束结果：当拟合具有常数暗能量状态方程参数$w$的模型时，CMB测量结果与BAO、超新星联合数据集之间存在明显张力；若允许$w$随时间变化，该张力会得到缓解。针对暗能量状态方程随时间演化、由$w_0$和$w_a$参数化的平坦宇宙，我们得到$(\rm{\u03A9_m},w_0,w_a) = (0.305\ub1780.004,-0.861^{+0.044}_{-0.042},-0.60^{+0.17}_{-0.19})$，暗能量品质因数为315，相比此前DES Y6、DESI-DR2与CMB联合约束的结果，$w_0-w_a$置信区域面积减少约30%。贝叶斯证据显示对随时间演化的暗能量仅有微弱偏好；而频率学派分析中，采用最大后验概率时，其相对于Flat-$\rm{\u039A}$CDM的偏好显著性为2.5$\u03C3$，采用最大似然时则为3.1$\u03C3$。
英文摘要
We present the Hubble diagram and cosmological constraints resulting from the combination of the Pantheon+ and DES-SN5YR supernova (SN) samples, which we refer to as Unite. Unite updates Pantheon+, including methodology improvements that the DES sample enabled, and adds the new SN from the DES survey. This represents the most comprehensive and internally consistent SN Ia dataset available, consisting of 2884 likely type Ia supernovae. This work features consistent SN Ia modelling, sample selection, and bias corrections. We also redetermine host-galaxy stellar masses for over 98% of the sample using a consistent framework. Using Unite alone, for a flat universe with a cosmological constant (Flat-$Λ$CDM), we find $Ω_{\rm m} = 0.310^{+0.012}_{-0.011}$. We further present constraints using the Unite sample combined with Cosmic Microwave Background and both DES and DESI Baryon Acoustic Oscillation data. We find strong evidence of tension between CMB measurements and the combined BAO and supernova datasets when fitting a model with constant dark energy equation of state ($w$), which is alleviated when allowing $w$ to vary with time. For a flat universe with dark energy that has a time-evolving equation of state parametrized by $w_0$ and $w_a$ we find $(Ω_{\rm m},w_0,w_a) = (0.305\pm0.004,-0.861^{+0.044}_{-0.042},-0.60^{+0.17}_{-0.19})$ with a dark energy Figure of Merit of 315. This corresponds to a $\sim30\%$ reduction in the area of the $w_0-w_a$ confidence region relative to previous constraints from the combination of DES Y6, DESI-DR2, and CMB data (arXiv:2605.27221). The Bayesian evidence indicates only weak preference for time evolving dark energy, whereas frequentist analyses yield a preference over Flat-$Λ$CDM at a significance of $3.3σ$ ($3.1σ$) when using the maximum $\textit{a posteriori}$ probability (maximum likelihood).
Comments26 pages, 22 figures. The Unite Hubble diagram and likelihood will be made publicly available upon acceptance of the paper; v2 Including a link to our Youtube Cosmology Talks video, see https://www.youtube.com/watch?v=KT-j65gRnOQ. Removed inactive datalinks, fixed MAP significance, and adjusted the manuscript format for submission to PASA. Submitted to PASA
