Study of Redshifted HI from the Epoch of Reionization with Drift scan

TL;DR

This paper explores using a drift scan strategy with interferometers like MWA to detect the Epoch of Reionization's 21-cm signal, highlighting potential advantages in stability and signal detection over traditional tracking methods.

Contribution

It formulates a novel drift scan approach for EoR detection, demonstrating its effectiveness and potential for improved signal-to-noise ratio compared to tracking strategies.

Findings

Drift scan can extend visibility correlation times to 1-2 hours.

The method achieves comparable or better SNR than tracking.

Bright point source inhomogeneity may help separate foregrounds.

Abstract

The detection of the Epoch of Reionization (EoR) in the redshifted 21-cm line is a challenging task. Here we formulate the detection of the EoR signal using the drift scan strategy. This method potentially has better instrumental stability as compared to the case where a single patch of sky is tracked. We demonstrate that the correlation time between measured visibilities could extend up to 1-2 hr for an interferometer array such as the Murchison Widefield Array (MWA), which has a wide primary beam. We estimate the EoR power based on cross-correlation of visibilities across time and show that the drift scan strategy is capable of the detection of the EoR signal with comparable/better signal-to-noise as compared to the tracking case. We also estimate the visibility correlation for a set of bright point sources and argue that the statistical inhomogeneity of bright point sources might allow their separation from the EoR signal.