Detection of Signals from Cosmic Reionization using Radio Interferometric Signal Processing

Abstract

Observations of the HI 21cm transition line promises to be an important probe into the cosmic dark ages and epoch of reionization. One of the challenges for the detection of this signal is the accuracy of the foreground source removal. This paper investigates the extragalactic point source contamination and how accurately the bright sources ($\gtrsim 1$ ~Jy) should be removed in order to reach the desired RMS noise and be able to detect the 21cm transition line. Here, we consider position and flux errors in the global sky-model for these bright sources as well as the frequency independent residual calibration errors. The synthesized beam is the only frequency dependent term included here. This work determines the level of accuracy for the calibration and source removal schemes and puts forward constraints for the design of the cosmic reionization data reduction scheme for the upcoming low frequency arrays like MWA,PAPER, etc. We show that in order to detect the reionization signal the bright sources need to be removed from the data-sets with a positional accuracy of $\sim 0.1$ arc-second. Our results also demonstrate that the efficient foreground source removal strategies can only tolerate a frequency independent antenna based mean residual calibration error of $\lesssim 0.2$ in amplitude or $\lesssim 0.2$ degree in phase, if they are constant over each days of observations (6 hours). In future papers we will extend this analysis to the power spectral domain and also include the frequency dependent calibration errors and direction dependent errors (ionosphere, primary beam, etc).

accepted by ApJ; 12 pages, 10 figures

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• Calibration Requirements for Detecting the 21 cm Epoch of Reionization Power Spectrum and Implications for the SKA
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• Systematic biases in low frequency radio interferometric data due to calibration: the LOFAR EoR case
• Visibility based angular power spectrum estimation in low frequency radio interferometric observations
• HI 21cm Cosmology and the Bi-spectrum: Closure Diagnostics in Massively Redundant Interferometric Arrays
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• The Bias and Uncertainty of Redundant and Sky-Based Calibration under Realistic Sky and Telescope Conditions
• Detailed study of ELAIS N1 field with the uGMRT -- II. Source Properties and Spectral Variation Of Foreground Power Spectrum from 300-500 MHz Observations
• Patterns of primary beam non-redundancy in close-packed 21 cm array observations
• Subtraction of Bright Point Sources from Synthesis Images of the Epoch of Reionization
• Validation of the HERA Phase I Epoch of Reionization 21 cm Power Spectrum Software Pipeline
• Detecting Cosmic Reionization using Bi-Spectrum Phase
• Detection of Cosmic Structures using the Bispectrum Phase. II. First Results from Application to Cosmic Reionization Using the Hydrogen Epoch of Reionization Array
• Deep wideband single pointings and mosaics in radio interferometry - How accurately do we reconstruct intensities and spectral indices of faint sources?
• Characterizing EoR foregrounds: A study of the Lockman Hole Region at 325 MHz
• Observing the Reionization : Effect of Calibration and Position Errors on Realistic Observation Conditions
• Probing early universe through redshifted 21-cm signal: Modelling and observational challenges
• Calibration Requirements for Epoch of Reionization 21-cm signal observations -- I. Effect of time-correlated gains
• Subtracting Foregrounds from Interferometric Measurements of the Redshifted 21 cm Emission
• Exploring Earth's Ionosphere and its effect on low radio frequency observation with the uGMRT and the SKA
• Validating a novel angular power spectrum estimator using simulated low frequency radio-interferometric data
• A Method to Extract the Angular Power Spectrum of the Epoch of Reionization from Low-Frequency Radio Interferometers
• Ionospheric effect on the synthetic Epoch of Reionization observations with the SKA1-Low
• Impact of Calibration and Position Errors on Astrophysical Parameters of the HI 21cm Signal
• Synthetic Observations with the Square Kilometre Array (SKA) -- development towards an end-to-end pipeline
• Mitigating gain calibration errors from EoR observations with SKA1-Low AA*
• Interpreting the HI 21-cm cosmology maps through Largest Cluster Statistics. Part II. Impact of the realistic foreground and instrumental noise on synthetic SKA1-Low observations