发表机构
Università degli Studi di Milano; INFN – Istituto Nazionale di Fisica Nucleare, Sezione di Milano; INAF – Istituto Nazionale di Astrofisica, Osservatorio Astrofisico di Brera-Merate; Università degli Studi di Torino; Instituto de Física de Cantabria (IFCA), CSIC-Univ. de Cantabria; Jodrell Bank Centre for Astrophysics, Department of Physics & Astronomy, The University of Manchester; Department of Physics & Astronomy, University of the Western Cape; INFN – Istituto Nazionale di Fisica Nucleare, Sezione di Torino（米兰大学; 意大利国家核物理研究所，米兰分部; 意大利国家天体物理研究所，布雷拉-梅拉特天文台; 都灵大学; 坎塔布里亚物理研究所（IFCA），西班牙国家研究委员会-坎塔布里亚大学; 曼彻斯特大学，物理学与天文学系，乔德雷尔银行天体物理学中心; 西开普大学，物理学与天文学系; 意大利国家核物理研究所，都灵分部）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
该研究利用MeerKAT在z=0.42处通过强度映射技术测量宇宙学尺度的HI 21厘米自谱，获得信噪比6.2的探测结果，测得成团振幅，为SKA巡天奠定基础。
AI 中文摘要
我们报告了一项对中性氢（HI）21厘米信号的直接测量，该测量通过强度映射技术在红移z=0.42处完成，测量范围为宇宙学尺度0.095 h Mpc⁻¹ < k < 0.245 h Mpc⁻¹的功率谱。我们分析了MeerKAT大天区巡天（MeerKLASS）2021年观测活动中观测到的频率范围971.2 MHz < ν < 1023.6 MHz的强度图，该巡天覆盖面积约236 deg²。利用该巡天的深度，我们将数据集划分为多个观测上独立的子集。在对每个子集独立进行盲干扰源分离后，我们利用内部互相关来抑制仪器噪声平台，并从残余系统误差中分离出宇宙学信号。尽管各子集的自谱显示存在过量功率，我们认为这与仍未解决的系统误差相关，但互谱测量通过了一系列零假设和稳健性检验。我们引入了一种多子集形式体系，以从内部互谱测量中推断HI自谱的振幅，同时边缘化数据处理过程中可能出现的信号损失，最终获得了信噪比为6.2的探测结果。我们根据HI宇宙丰度及其线性偏置来约束信号的成团振幅，测得10³ Ω_HI b_HI = 1.271⁺¹·⁰⁸⁰₋₀·⁵⁹⁸。这项直接测量标志着证明HI强度映射技术对未来平方公里阵列天文台（SKA Observatory，MeerKAT是其 precursor）巡天有效性的一个里程碑。
英文摘要
We report a direct measurement of the 21-cm signal from neutral hydrogen (HI) via the intensity mapping technique at redshift $z = 0.42$ through its power spectrum at cosmological scales $0.095\,h\,{\rm Mpc}^{-1}<k<0.245\,h\,{\rm Mpc}^{-1}$. We analyse intensity maps observed in the frequency range $971.2\,{\rm MHz}<ν<1023.6\,{\rm MHz}$ during the 2021 observational campaign of the MeerKAT Large Area Synoptic Survey (MeerKLASS) spanning an area of approximately $236\,{\rm deg}^2$. Capitalising on the depth of this survey, we divide the data set into multiple observationally independent subsets. After performing blind contaminant separation independently on each subset, we exploit internal cross-correlations to suppress the instrumental noise plateau and isolate the cosmological signal from residual systematics. Although the subsets' auto-spectra show the presence of excess power that we deem linked to still unresolved systematics, the cross-spectra measurements satisfactorily pass a battery of null and robustness tests. We introduce a multi-subset formalism to infer the amplitude of the HI auto-spectrum from our internal cross-spectra measurements while marginalising the potential signal loss that occurs during data processing, reaching a detection with signal-to-noise ratio of 6.2. We constrain the clustering amplitude of the signal in terms of the HI cosmic abundance and its linear bias, measuring $10^3\,Ω_{\rm HI} b_{\rm HI}=1.271^{+1.080}_{-0.598}$. This direct measurement marks a milestone in demonstrating the effectiveness of the HI intensity mapping technique for future surveys with the SKA Observatory, of which MeerKAT is a precursor.
Comments34 pages, 32 figures. Accepted for publication by MNRAS on 01/10/2026
