Enhancing EoR limits – spectral accuracy of the MWA

Wed 6 June, 2018 @12:00 PM, level 7
Dr. Nichole Barry, Postdoctoral Researcher
University of Melbourne 

Email:  nichole.barry[at]unimelb.edu.au

Abstract
Epoch of Reionization observations have the potential to be transformative in the field of cosmology, but this is impossible without unprecedented levels of accuracy in calibration. We enhance EoR upper limits from the Murchison Widefield Array through the improvement of instrumental calibration with in situ simulations, and the reduced limit highlights the precision and accuracy that we must achieve. An in situ calibration simulation verifies our experimental findings, and identifies the fundamental limits of sky-based calibration. We set a precedent for required bandpass accuracy to one part in 10⁵

Our improved EoR upper limit is (80 mK)² at k=0.2 h Mpc^-1 for z=7, an improvement of over a factor of 4 compared to a previous analysis using the exact same data set. These spectral accuracy techniques will influence future pipeline advances in the search for the EoR.