Description
In the late Universe, neutral hydrogen (HI) is found inside dark matter haloes hosting galaxies. Using a technique called intensity mapping, the distribution of HI can be used as a tracer for large-scale structures. The accessible scales from the data depend on the instrument used, i.e. single dish telescope or interferometer. Radio interferometers are sensitive to scales that simultaneously probe large-scale structure cosmology and local astrophysics. Thus, interferometric HI intensity mapping surveys can simultaneously constrain astrophysical and cosmological parameters. The advent of the SKAO precursor MeerKAT has started producing surveys with sufficient sensitivity to statistically probe this gas in galaxies. I will present the results of HI intensity mapping at low redshift (z<0.5) using MeerKAT surveys. These results directly affect the expectation from SKAO since the data emulates many of the challenges imminent for SKA-mid data. I will discuss the new methodologies we have developed for intensity mapping. This led to the first detection of the HI auto-correlation power spectrum at z<0.5 with a high statistical significance and constraints on the abundance and distribution of HI. I will also discuss our efforts to combine multi-pointing interferometric surveys for intensity mapping. The techniques developed have led to the first upper limits on the HI auto-correlation power spectrum from the MIGHTEE survey. Finally, I will show the prospects of intensity mapping with the SKAO using the lessons learned from the precursor data.
