The nature of the time correlated noise component (the 1/f noise) of single dish radio telescopes is critical to the detectability of the HI signal in intensity mapping experiments. In this paper, we present the 1/f noise properties of the MeerKAT receiver system using South Celestial Pole (SCP) tracking data. We estimate both the temporal power spectrum density and the 2D power spectrum density for each of the antennas and polarizations. We apply Singular Value Decomposition (SVD) to the dataset and show that, by removing the strongest components, the 1/f noise can be drastically reduced, indicating that it is highly correlated in frequency. Without SVD mode subtraction, the knee frequency over a $20\,$MHz integration is higher than $0.1\,\rm Hz$; with just $2$~mode subtraction, the knee frequency is reduced to $\sim 3\times 10^{-3}\,{\rm Hz}$, indicating that the system induced 1/f-type variations are well under the thermal noise fluctuations over a few hundred seconds time scales. The 2D power spectrum shows that the 1/f-type variations are restricted to a small region in the time-frequency space, either with long wavelength correlations in frequency or in time. This gives a wide range of cosmological scales where the 21cm signal can be measured without further need to calibrate the gain time fluctuations. Finally, we demonstrate that a simple power spectrum parameterization is sufficient to describe the data and provide fitting parameters for both the 1D and 2D power spectrum.
Cross-correlating Squared kSZ and HI Intensity Fields: A Map-level ACT--MeerKAT Forecast
National Astronomical Observatories, Chinese Academy of Sciences（中国科学院国家天文台）；School of Astronomy and Space Science, University of Chinese Academy of Sciences (UCAS)（中国科学院大学天文与空间科学学院）；Asia Pacific Center for Theoretical Physics (APCTP)（亚太理论物理中心）；Department of Physics, College of Sciences, Northeastern University（东北大学理学院物理系）
Cosmological Prediction from the joint observation of MeerKAT and CSST at $z$ = 0.4 $\sim$ 1.2
National Astronomical Observatories, Chinese Academy of Sciences（中国科学院国家天文台）；School of Astronomy and Space Science, University of Chinese Academy of Sciences(UCAS)（中国科学院大学天文与空间科学学院）；Department of Physics, Stellenbosch University（斯泰伦博斯大学物理系）；Science Center for Chinese Space Station Survey Telescope, National Astronomical Observatories, Chinese Academy of Science（中国科学院国家天文台中国空间站巡天望远镜科学中心）
HI intensity mapping with MeerKAT: A measurement of the 21-cm auto-spectrum on cosmological scales
Università degli Studi di Milano（米兰大学）；INFN – Istituto Nazionale di Fisica Nucleare, Sezione di Milano（意大利国家核物理研究所，米兰分部）；INAF – Istituto Nazionale di Astrofisica, Osservatorio Astrofisico di Brera-Merate（意大利国家天体物理研究所，布雷拉-梅拉特天文台）；Università degli Studi di Torino（都灵大学）；Instituto de Física de Cantabria (IFCA), CSIC-Univ. de Cantabria（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）；Jodrell Bank Centre for Astrophysics, Department of Physics & Astronomy, The University of Manchester（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）；Department of Physics & Astronomy, University of the Western Cape（西开普大学，物理学与天文学系）；INFN – Istituto Nazionale di Fisica Nucleare, Sezione di Torino（意大利国家核物理研究所，都灵分部）
Single-dish HI Intensity Mapping with the SKAO: Precursor Progress with MeerKAT's Large Area Synoptic Survey (MeerKLASS)
University of Portsmouth（朴茨茅斯大学）；The University of Manchester（曼彻斯特大学）；Shanghai Astronomical Observatory, Chinese Academy of Sciences（中国科学院上海天文台）；University of the Western Cape（西开普敦大学）；Institute for Fundamental Physics of the Universe（宇宙基础物理研究所）；The University of Edinburgh（爱丁堡大学）；University of Cambridge（剑桥大学）；Northeastern University（东北大学）；Observatoire de la Côte d’Azur（蔚蓝海岸天文台）
Interferometric HI Intensity Mapping of the Late Time Universe with SKA-Mid
The University of Manchester（曼彻斯特大学）；The University of Edinburgh（爱丁堡大学）；University of the Western Cape（西开普敦大学）；Tsinghua University（清华大学）；Université Paris-Saclay（巴黎萨克雷大学）；Université Paris Cité（巴黎西岱大学）
Revealing cosmological fluctuations in 21cm intensity maps with MeerKLASS: from maps to power spectra
University of Portsmouth（朴茨茅斯大学）；The University of Manchester（曼彻斯特大学）；Università degli Studi di Milano（米兰大学）；INFN – Istituto Nazionale di Fisica Nucleare（意大利国家核物理研究所）；INAF – Istituto Nazionale di Astrofisica（意大利国家天体物理研究所）；Università degli Studi di Torino（都灵大学）；Instituto de Física de Cantabria (IFCA), CSIC-Univ. de Cantabria（坎塔布里亚物理研究所（CSIC-坎塔布里亚大学））；Department of Physics & Astronomy, University of the Western Cape（西开普大学物理与天文系）
Detecting redshift space distortions with forthcoming 21cm intensity maps from MeerKLASS
University of Portsmouth（朴茨茅斯大学）；The University of Edinburgh（爱丁堡大学）；Instituto de Física de Cantabria (IFCA), CSIC-Univ. de Cantabria（坎塔布里亚物理研究所（IFCA），西班牙科学研究中心-坎塔布里亚大学）
Generalised Visibility ILC: a new foreground mitigation strategy for interferometric HI intensity mapping in the low-redshift Universe
Instituto de Física de Cantabria (CSIC-Universidad de Cantabria)（坎塔布里亚物理研究所）；Dpto. de Física Moderna, Universidad de Cantabria（坎塔布里亚大学现代物理系）；Jodrell Bank Centre for Astrophysics, Department of Physics and Astronomy, The University of Manchester（曼彻斯特大学天体物理学乔德雷尔银行中心）；State Key Laboratory of Radio Astronomy and Technology, Shanghai Astronomical Observatory, CAS（中国科学院上海天文台射电天文与技术国家重点实验室）
Looking for Population III stars with He II line intensity mapping
限制第三星族（Pop III）恒星的性质将是非常具有挑战性的，因为它们居住在高红移的小星系中，这将难以直接检测到。在本文中，我们认为，强度映射可能是一个很有前途的方法来研究Pop III星。强度测绘是一种在三维空间中测量星系线辐射的大尺度波动而不需要分辨单个源的技术。这项技术非常适合观测许多暗淡的星系，因为它可以测量它们的累积发射，即使它们不能被直接探测到。我们专注于强度映射的He II复合线。这些谱线在Pop III星中比Pop II星强得多，因为Pop III星的更硬的光谱预计会产生许多He II电离光子。测量He II 1640的强度映射信号，以及来自其他谱线如Ly $α$、H $α$和金属谱线的信号，可以给出Pop III恒星的初始质量函数（IMF）和恒星形成率密度（SFRD）作为红移的函数的约束。为了证明这些观测结果的可行性，我们估计了来自$z=10-20$的Pop III He II 1640射电强度映射信号的强度。我们表明，在$z\approx10$，信号可以准确地测量由两个不同的假设未来的仪器，互相关的He II 1640与CO（1-0）线发射的星系和其他21厘米发射的星系际介质（IGM）。
