M. Barberi-Squarotti, J. L. Bernal, P. Bull, S. Camera, I. P. Carucci, Z. Chen, S. Cunnington, B. N. Engelbrecht, J. Fonseca, K. Grainge, M. O. Irfan, Y. Li, A. Mazumder, S. Paul, A. Pourtsidou, M. G. Santos, M. Spinelli, J. Wang, A. Witzemann, L. Wolz
Abstract
We present results from MeerKAT single-dish H I intensity maps, the final observations to be performed in L-band in the MeerKAT Large Area Synoptic Survey (MeerKLASS) campaign. The observations represent the deepest single-dish H I intensity maps to date, produced from 41 repeated scans over 236 deg2, providing 62 hours of observational data for each of the 64 dishes before flagging. By introducing an iterative self-calibration process, the estimated thermal noise of the reconstructed maps is limited to ~ 1.21 mK (1.2 × the theoretical noise level). This thermal noise will be sub-dominant relative to the H I fluctuations on large scales (k ≲ 0.15 h Mpc-1), which demands upgrades to power spectrum analysis techniques, particularly for covariance estimation. In this work, we present the improved MeerKLASS analysis pipeline, validating it on both a suite of mock simulations and a small sample of overlapping spectroscopic galaxies from the Galaxy And Mass Assembly (GAMA) survey. Despite only overlapping with ~ 25% of the MeerKLASS deep field, and a conservative approach to covariance estimation, we still obtain a > 4 σ detection of the cross-power spectrum between the intensity maps and the 2269 galaxies at the narrow redshift range 0.39 < z < 0.46. We briefly discuss the H I auto-power spectrum from this data, the detection of which will be the focus of follow-up work. For the first time with MeerKAT single-dish intensity maps, we also present evidence of H I emission from stacking the maps onto the positions of the GAMA galaxies.
Keywords
methods: data analysis, methods: statistical, large scale structure of Universe, cosmology: observations, radio lines: general
Monthly Notices of the Royal Astronomical Society
Volume 537, Issue 4, Page 3632
2025 March
