MeerKLASS L-band deep-field intensity maps: entering the H <scp>i</scp> dominated regime

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 $236\, \deg ^2$, providing 62 h 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 ${\sim }\, 1.21$ mK ($1.2\, \times$ the theoretical noise level). This thermal noise will be subdominant relative to the H i fluctuations on large scales ($k\, {\lesssim }\, 0.15\, h\, \text{Mpc}^{-1}$), 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 ${\sim }\, 25~{{\ \rm per\ cent}}$ of the MeerKLASS deep field, and a conservative approach to covariance estimation, we still obtain a ${\gt }\, 4\, \sigma$ detection of the cross-power spectrum between the intensity maps and the 2269 galaxies at the narrow redshift range $0.39\, {\lt }\, z\, {\lt }\, 0.46$. We briefly discuss the H i autopower spectrum from these 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.

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Journal
Monthly Notices of the Royal Astronomical Society
Published
2025-02-03
DOI
https://doi.org/10.1093/mnras/staf195
Citations
21
Primary Topic
Galaxies: Formation, Evolution, Phenomena
Type
article
Field-Weighted Citation Impact
24.25

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article

MeerKLASS L-band deep-field intensity maps: entering the H i dominated regime

José Fonseca, Piyanat Kittiwisit, Mário G. Santos, Marta Spinelli et al.
21 citations
Monthly Notices of the Royal Astronomical Society
Galaxies: Formation, Evolution, Phenomena
24.25
article

MeerKLASS L-band deep-field intensity maps: entering the H i dominated regime

José Fonseca, Piyanat Kittiwisit, Mário G. Santos, Marta Spinelli, Philip Bull, Wenkai Hu, Isabella P. Carucci, Brandon Engelbrecht, Laura Wolz, Melis O Irfan, Alkistis Pourtsidou, Zhaoting Chen, S. Camera, Steven Cunnington, K. Grainge, Aishrila Mazumder, Sourabh Paul, Amadeus Witzemann, Tamirat G. Gogo, Jingying Wang, Suman Chatterjee, Matilde Barberi-Squarotti, José L Bernal, Yichao Li, Sifiso Mahlalela
article en
21 citations

Abstract

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 $236\, \deg ^2$, providing 62 h 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 ${\sim }\, 1.21$ mK ($1.2\, \times$ the theoretical noise level). This thermal noise will be subdominant relative to the H i fluctuations on large scales ($k\, {\lesssim }\, 0.15\, h\, \text{Mpc}^{-1}$), 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 ${\sim }\, 25~{{\ \rm per\ cent}}$ of the MeerKLASS deep field, and a conservative approach to covariance estimation, we still obtain a ${\gt }\, 4\, \sigma$ detection of the cross-power spectrum between the intensity maps and the 2269 galaxies at the narrow redshift range $0.39\, {\lt }\, z\, {\lt }\, 0.46$. We briefly discuss the H i autopower spectrum from these 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.

Monthly Notices of the Royal Astronomical SocietyVol. 537(4)
Universidade do Porto (PT), University of Milan (IT), University of Cambridge (GB), Shanghai Astronomical Observatory (CN), Trieste Astronomical Observatory (IT), Brera Astronomical Observatory (IT), University of Manchester (GB), Institute of Astrophysics and Space Sciences (PT), Istituto Nazionale di Fisica Nucleare, Sezione di Torino (IT), Osservatorio Astrofisico di Torino (IT), Royal Observatory (GB), South African Radio Astronomy Observatory (ZA), Institute of Astronomy (RU), Observatoire de la Côte d’Azur (FR), Istituto Nazionale di Fisica Nucleare, Sezione di Milano (IT), Institute for Fundamental Physics of the Universe (IT), Instituto de Física de Cantabria (ES), University of Turin (IT), University of the Western Cape (ZA), National Institute for Astrophysics (IT), Northeastern University (CN), University of Edinburgh (GB)
UK Research and Innovation, European Commission, National Research Foundation, Ministerio de Ciencia e Innovación, Fundação para a Ciência e a Tecnologia, H2020 European Research Council
Openalex Percentile: Top 0%
Galaxies: Formation, Evolution, Phenomena
24.25
DOIOpen Access PDFOpenAlex
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