Finding the Origin of Gas in Galaxies with MeerKAT

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Neutral hydrogen drives galaxy evolution. It is the fuel for star formation. However, there is not enough present in galaxies to sustain star formation over the lifetime of the universe. Galaxies must acquire their gas from an external source through an — as yet — undetected process. MeerGas will identify how galaxies replenish their gas supply and will thereby deepen our understanding of galaxy evolution. Simulations suggest that filaments of gas, which transfer intergalactic material, feed many galaxies. This process, called cold accretion, has not been observed directly as it needs sensitive observations that are virtually impossible with current telescopes. The new MeerKAT radio telescope in South Africa, the largest cm-wave synthesis radio telescope in the southern hemisphere, will fundamentally change this. MeerGas uses high-resolution, high-sensitivity 3D observations of neutral hydrogen in 30 nearby galaxies obtained from the MHONGOOSE Large Survey Project, the highest-ranked MeerKAT imaging key survey. Uniquely, these observations probe structures up to two orders of magnitude fainter than in previous nearby galaxy neutral hydrogen surveys. The MeerGas analysis of these data will be unparalleled in its ability to determine the nature of accretion. MeerGas will be the only systematic study of accretion at high resolution and high sensitivity until the completion of the Square Kilometre Array in a decade. The analysis of these unique data will be a challenge as the data volume will be two orders of magnitude larger than all recent nearby galaxy neutral hydrogen surveys combined. Through my extensive experience in nearby galaxies research and neutral hydrogen observations, I am uniquely qualified to lead this ambitious project, which will yield precision studies of the accretion processes in galaxies over a wide range of physical conditions and addresses an unanswered key question in galaxy evolution.