Cosmology seminar: Cosmology with the SKA Pathfinder

The SKA observatory, and the pathfinder experiments that lead up to it, will provide extragalactic radio data over the largest scales of the universe. ASKAP, the Australian Square Kilometre Array Pathfinder, is already providing early survey data in the form of radio continuum catalogues from the RACS (Rapid ASKAP Continuum Survey) and EMU (Evolutionary Map of the Universe) survey. In my talk I will introduce RACS and EMU, and show recent results, including a measurement of the Integrated Sachs-Wolfe effect from cross-correlating the cosmic microwave background maps from the Planck satellite with the RACS catalogue. We detect a positive cross-correlation at ~2.8sigma relative to the null hypothesis of no correlation, but also detect a power excess in the galaxy auto- correlation angular power spectrum on large scales (l ≤ 40), and investigate possible systematic causes. Analysis methods to deal with such large-scale systematics will need to be developed for the next generation of large-area continuum surveys.