Observing the Reionization : Effect of Calibration and Position Errors on Realistic Observation Conditions

TL;DR

This study evaluates how calibration and position errors impact the detection of the 21-cm cosmological signal using different radio telescope arrays, providing insights into optimal observational tolerances.

Contribution

It introduces an end-to-end simulation pipeline for assessing the effects of systematic errors on 21-cm signal detection across multiple radio arrays.

Findings

Calibration error tolerance is approximately 0.01% for signal detection.

Position errors greater than 5 arcseconds obscure the cosmological signal.

SKA1-Low performs slightly better in image detection, MWA in power spectrum analysis.

Abstract

Observation of the redshifted 21-cm signal from Cosmic Dawn and Epoch of Reionization is a challenging endeavor in observational cosmology. Presence of orders of magnitude brighter astrophysical foregrounds and various instrumental systematics increases the complexity of these observations. This work presents an end-to-end pipeline dealing with synthetic interferometric data of sensitive radio observations . The mock sky model includes the redshifted 21-cm signal and astrophysical foregrounds. The effects of calibration error and position error in the extraction of the redshifted 21-cm power spectrum has been simulated. The effect of the errors in the image plane detection of the cosmological signal has also been studied. A comparative analysis for array configurations like the SKA1-Low, MWA and HERA has been demonstrated. The calibration error tolerance of the arrays, under some assumptions about the nature of the systematic components, is optimally found to be $\sim 0.01\%$ for the detection of the signal. For position errors, an offset of $\gtrapprox 5\arcsec$ makes the residual foregrounds obscure the target signal. These simulations also imply that in the SKA-1 Low performs marginally better than the others in the image domain, while the same is true for MWA in the power spectrum domain. This is one of the first studies that compares performance of various radio telescopes operating under similar observing conditions towards detecting the cosmological signal. This end-to-end pipeline can also be extended to study effects of chromatic primary beam, radio frequency inferences, foregrounds with spectral features, etc.