Galaxy Evolution with HI Intensity Mapping

Abstract: Intensity mapping surveys of neutral hydrogen (HI) are a novel way to measure the large scale matter distribution of our Universe and thus constrain cosmological parameters describing the Universal expansion. The next generation of radio telescopes and interferometers are being designed and built to optimise the detection of the HI line at low spatial resolution allowing efficient mapping of large volumes. The impact of instrumental systematics of radio observations on cosmological measurements can be significantly reduced by cross- correlating the HI signal with galaxy surveys. The cross-correlation also offers an innovative way to statistically detect the average HI content of the optically-selected galaxy sample since the noise on the cross-power spectrum measurement scales with the galaxy HI temperature. I will give an introduction into the intensity mapping technique and the prospects of future and on-going experiments, with focus on the Square Kilometre Array (SKA). After an overview on foreground mitigation methods, I will present a study on the potential of future intensity mapping cross-correlation projects in constraining galaxy evolution processes. I will show how the SKA pathfinder experiments can detect the relevant scales of the cross-power spectrum and probe the HI content of medium redshift galaxies to faint for direct detection with radio telescopes.

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