Paul, SourabhChen, ZhaotingSantos, Mario G.Wolz, Laura2026-08-182026-08-182026Paul, S., Chen, Z., Santos, M.G. and Wolz, L., 2026. A Direct Detection of Neutral Hydrogen Intensity Mapping on Mpc Scales at z≈ 0.32 and z≈ 0.44. The Astrophysical Journal Letters, 1005(2), p.L56.https://doi.org/10.3847/2041-8213/ae808fhttps://hdl.handle.net/10566/25188We report the detection of the cosmological power spectrum using the intensity mapping signal from 21 cm emission of neutral hydrogen (H I), derived from interferometric observations with the L-band receivers of the MeerKAT radio telescope. Intensity mapping is a promising technique to map the three-dimensional matter distribution of the Universe at radio frequencies and probe the underlying cosmology. So far, detections have only been achieved through cross-correlations with galaxy surveys. Here we present independent measurements of the H I power spectrum at redshifts 0.32 and 0.44 with the foreground avoidance method. We utilize two distinct frameworks for mitigating systematics: a conservative baseline-flagging-based approach achieves detections at 3.2σ and 3.5σ, and a power-spectrum-based flagging method enhances the significance to 5.9σ and 9.18σ, respectively. The information contained in the power spectrum measurements allows us to probe the parameters of the H I mass function and H I halo model. These results are a significant step toward precision cosmology with H I intensity mapping using the new generation of radio telescopes. © 2026. The Author(s). Published by the American Astronomical Society. Original content from this work may be used under the terms of the https://creativecommons.org/licenses/by/4.0/. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI.enCosmology (343)Large-scale structure of the universe (902)Radio galaxies (1343)Radio interferometers (1345)Neutral HydrogenArticle