发表机构
Universitat de Barcelona; Aix Marseille Université; CNRS/IN2P3; CPPM; Institut d’Estudis Espacials de Catalunya; Institució Catalana de Recerca i Estudis Avançats（巴塞罗那大学; 艾克斯-马赛大学; 法国国家科学研究中心/国家核物理与粒子物理研究所; 马赛粒子物理中心; 加泰罗尼亚空间研究所; 加泰罗尼亚高级研究学院）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本文利用DESI DR1数据开展角向BAO分析，通过角相关函数直接测量横向膨胀参数，与3D结果一致，并给出宇宙学参数约束。
AI 中文摘要
我们提出了利用DESI DR1数据进行的角向BAO分析，作为DESI主要3D BAO分析的补充方法。我们使用两点角相关函数$w(\theta)$，在红移壳层$\delta z = 0.02, 0.05$内进行分析，覆盖红移范围$0.4 < z < 2.1$，使用的DESI示踪天体包括：LRG1、LRG2、LRG3+ELG1、ELG2和QSO。该方法的主要优势在于无需假设基准宇宙学模型即可将红移转换为距离，并能直接测量横向膨胀参数$\alpha_{\perp}(z)$。我们使用在基准宇宙学中构建的模板以及基于1000个EZmock模拟实现的协方差，对每个示踪天体拟合一个共享的$\alpha_{\perp}(z)$。我们在每个示踪天体区间内以$2.5\\%$至$4.2\\%$的精度测量了$\alpha_\perp$。与DESI DR1 3D分析中相同示踪天体得到的$D_M/r_{\rm d}$测量值相比，我们的结果在统计精度内是一致的。我们没有发现2D和3D分析之间横向BAO尺度存在偏移的证据。仅对$\alpha_\perp(z)$进行平坦$\Lambda$CDM拟合，得到$\Omega_{\rm m} = 0.198^{+0.045}_{-0.068}$，比DESI 3D值低$1.6\sigma$，该偏差主要由$z = 1.49$的QSO区间主导，其$\alpha_\perp(z=1.49)=1.058\pm0.028$比基准值高约$2\sigma$。仅使用LRG和ELG时，我们的$\Omega_{\rm m}$和$H_0 r_{\rm d}$与相同区间上的3D仅横向拟合结果在优于$0.1\sigma$的范围内一致。加入BBN先验后，完整的2D样本给出$H_0 = 63.9^{+1.9}_{-3.3}\\, {\rm km\\,s^{-1}\\,Mpc^{-1}}$。该流程可应用于未来的DESI数据发布，届时体积和采样密度的增加将决定QSO偏移是否持续存在，并进一步收紧2D BAO约束。
英文摘要
We present the angular BAO analysis using DESI DR1 data as a complementary approach to DESI's primary 3D BAO analysis. We perform the analysis using the two-point angular correlation function $w(θ)$ in tomographic redshift shells of $δz = 0.02, 0.05$, spanning the redshift range $0.4 < z < 2.1$ using the DESI tracers: LRG1, LRG2, LRG3+ELG1, ELG2 and QSO. The main benefit is that it requires no fiducial cosmology to convert redshifts into distances and yields a direct measurement of the transverse dilation parameter $α_{\perp}(z)$. We fit each tracer with a single shared $α_{\perp}(z)$ using templates constructed in a fiducial cosmology and a mock-based covariance from 1000 EZmock realisations. We measure $α_\perp$ to $2.5$ -- $4.2\%$ precision in each tracer bin. Compared to the $D_M/r_{\rm d}$ measurements obtained from the DESI DR1 3D analysis for the same tracers, our results are consistent within the statistical precision. We find no evidence for a shift in the transverse BAO scale between the 2D and 3D analyses. Flat $Λ$CDM fits to $α_\perp(z)$ alone give $Ω_{\rm m} = 0.198^{+0.045}_{-0.068}$, $1.6σ$ below the DESI 3D value, and the pull is dominated by the $z =1.49$ QSO bin, whose $α_\perp(z=1.49)=1.058\pm0.028$ sits $\sim 2σ$ above the fiducial. Restricting to LRGs and ELGs only, our $Ω_{\rm m}$ and $H_0 r_{\rm d}$ agree with the 3D transverse-only fit over the same bins to better than $0.1σ$. With an additional BBN prior, the full 2D sample gives $H_0 = 63.9^{+1.9}_{-3.3}\, {\rm km\,s^{-1}\,Mpc^{-1}}$. This pipeline is implementable on forthcoming DESI data releases, where the increase in volume and sampling density will determine if the QSO offset persists and will also tighten 2D BAO constraints.
Comments42 pages, 13 figures
