Exploring the Dark Ages and Epoch of Reionization with the HI 21 cm signal

Abstract

Observations of the HI 21 cm transition line promises to be an important probe into the cosmic Dark Ages and Epoch of Reionization. Detection of this redshifted 21 cm signal is one of the key science goal for several upcoming and future low frequency radio telescopes like Murchison Widefield Array (MWA), Precision Array to Probe Epoch of Reionization (PAPER), LOw Frequency ARray (LOFAR) and Square Kilometer Array (SKA). One of the challenges for the detection of this signal is the accuracy of the foreground source removal. Here, we investigate the level of accuracy for the calibration and bright source removal algorithms from the reionization data-sets. We also put forward constraints for the design of the cosmic reionization data reduction scheme for the upcoming low frequency arrays such as, MWA, PAPER, etc. We show that the efficient foreground source removal strategies can only tolerate a frequency independent antenna based mean residual calibration error of 0.2% in amplitude or 0.2 degrees in phase. In order to extract the spherically averaged HI signal power spectrum, bright foregrounds need to be removed with calibration accuracies of 0.05% in amplitude. We also demonstrate the advantages of probing the cosmic reionization with the two dimensional HI power spectrum.