The Murchison Widefield Array 21cm Epoch of Reionization Experiment: Design, Construction, and First Season Results

Abstract

The Cosmic Dark Ages and the Epoch of Reionization (EoR) remain largely unexplored chapters in the history and evolution of the Universe. These periods hold the potential to inform our picture of the cosmos similar to what the Cosmic Microwave Background has done over the past several decades. A promising method to probe the neutral hydrogen gas between early galaxies is known as 21cm tomography, which utilizes the ubiquitous hyper-fine transition of HI to create 3D maps of the intergalactic medium. The Murchison Widefield Array (MWA) is an instrument built with a primary science driver to detect and characterize the EoR through 21cm tomography. In this thesis we explore the challenges faced by the MWA from the layout of antennas, to a custom analysis pipeline, to bridging the gap with probes at other wavelengths. We discuss many lessons learned in the course of reducing MWA data with an extremely precise measurement in mind, and conclude with the first deep integration from array. We present a 2-$\sigma$ upper limit on the EoR power spectrum of $\Delta^2(k)<1.25\times10^4$ mK$^2$ at cosmic scale $k=0.236$ h Mpc$^{-1}$ and redshift $z=6.8$. Our result is a marginal improvement over previous MWA results and consistent with the best published limits from other instruments. This result is the deepest imaging power spectrum to date, and is a major step forward for this type of analysis. While our limit is dominated by systematics, we offer strategies for improvement for future analysis.