A STUDY OF FUNDAMENTAL LIMITATIONS TO STATISTICAL DETECTION OF REDSHIFTED H I FROM THE EPOCH OF REIONIZATION

Abstract

In this paper we explore for the first time the relative magnitudes of three\nfundamental sources of uncertainty, namely, foreground contamination, thermal\nnoise and sample variance in detecting the HI power spectrum from the Epoch of\nReionization (EoR). We derive limits on the sensitivity of a Fourier synthesis\ntelescope to detect EoR based on its array configuration and a statistical\nrepresentation of images made by the instrument. We use the Murchison Widefield\nArray (MWA) configuration for our studies. Using a unified framework for\nestimating signal and noise components in the HI power spectrum, we derive an\nexpression for and estimate the contamination from extragalactic point-like\nsources in three-dimensional k-space. Sensitivity for EoR HI power spectrum\ndetection is estimated for different observing modes with MWA. With 1000 hours\nof observing on a single field using the 128-tile MWA, EoR detection is\nfeasible (S/N > 1 for $k\\lesssim 0.8$ Mpc$^{-1}$). Bandpass shaping and\nrefinements to the EoR window are found to be effective in containing\nforeground contamination, which makes the instrument tolerant to imaging\nerrors. We find that for a given observing time, observing many independent\nfields of view does not offer an advantage over a single field observation when\nthermal noise dominates over other uncertainties in the derived power spectrum.\n