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arxiv: 2301.11943 · v2 · pith:F6TN5PCJnew · submitted 2023-01-27 · 🌌 astro-ph.CO · astro-ph.GA

A direct detection of neutral hydrogen intensity mapping on Mpc scales at zapprox 0.32 and zapprox 0.44

classification 🌌 astro-ph.CO astro-ph.GA
keywords intensitymappingpowersigmaspectrumradioapproxcosmology
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We report the detection of the cosmological power spectrum using the intensity mapping signal from 21-cm emission of neutral hydrogen (HI), 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 HI power spectrum at redshifts $0.32$ and $0.44$ with the foreground avoidance method. We utilize two distinct frameworks for mitigating systematics, where a conservative baseline flagging based approach achieves detections at $3.2\sigma$ and $3.5\sigma$, and a power spectrum based flagging method enhances the significance to $5.9\sigma$ and $9.18\sigma$, respectively. The information contained in the power spectrum measurements allows us to probe the parameters of the HI mass function and HI halo model. These results are a significant step towards precision cosmology with HI intensity mapping using the new generation of radio telescopes.

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