DESI DR2 重子声学振荡的统一示踪剂分析
A Unified Tracer Analysis of DESI DR2 Baryon Acoustic Oscillations
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中文总结 AI 辅助
该研究改进DESI DR2重子声学振荡分析的样本组合方法，构建统一示踪剂，完成距离测量与系统误差测试，精细解析红移-距离关系，验证了膨胀历史与暗能量状态方程的相关结论。
中文摘要 AI 辅助
我们在DESI重子声学振荡分析中，对先前优化重叠星系样本组合的工作进行了改进。通过用线性偏置（linear bias）对每个星系加权，将重叠星系合并为单一统一目录，自然避免了宇宙体积的重复计数，并在目录层面纳入了所有自相关与交叉相关信息。相较于先前工作的改进包括：添加红移z=1.6内的类星体（QSO）以涵盖所有重叠的DR2示踪剂，以及采用红移依赖的偏置处理以提升重建效果。我们利用该统一示踪剂报告了距离测量结果，发现其与基线DR2 BAO分析高度一致。我们还测试了DESI数据中依赖示踪剂的系统误差，发现在0.8<z<1.6范围内无此类系统误差的证据。最后，我们利用统一示踪剂对分析进行红移重分箱，以更精细地解析红移-距离关系。该精细红移分箱下的动力学暗能量结果表明，在0.8<z<1.6的红移范围内，膨胀历史中不存在遗漏特征，且重现了DESI对演化暗能量状态方程的偏好。
英文摘要
We improve upon previous efforts to optimally combine overlapping galaxy samples in the DESI baryon acoustic oscillation analysis. By weighting each galaxy by its linear bias, overlapping galaxies are combined into a single, unified catalog, naturally avoiding double counting of cosmic volume and including all auto- and cross- information at the catalog level. Improvements over the previous effort include the addition of QSO out to $z=1.6$ to account for all overlapping DR2 tracers and redshift-dependent bias treatment to improve reconstruction. We report distance measurements using this unified tracer, and find them to be highly consistent with the baseline DR2 BAO analysis. We also test for tracer-dependent systematics within the DESI data, and find no evidence of tracer-dependent systematics within $0.8<z<1.6$. Finally, we take advantage of the unified tracer to rebin the analysis in redshift in order to more finely resolve the redshift-to-distance relation. Dynamical dark energy results on this finer redshift binning indicate that there is no missed feature in the expansion history in the redshifts $0.8<z<1.6$, and reproduces DESI's preference for an evolving dark energy equation of state.
