Mitigating gain calibration errors from EoR observations with SKA1-Low AA*

Abstract

The observations of the redshifted 21-cm signal from neutral hydrogen are a promising probe for understanding the Cosmic Dawn and the Epoch of Reionisation (EoR). One of the primary obstacles to the statistical detection of the Cosmological signal is the presence of residual foreground arising from gain calibration errors. Previous studies have shown that gain calibration errors as small as 0.01$\%$ can lead to a biased interpretation of the observed signal power spectrum estimation, by nearly an order of magnitude. A recent study further highlights that to accurately retrieve astrophysical parameters, the threshold gain calibration error should be below 0.01$\%$. This work investigates the impact of residual extragalactic foregrounds arising from gain calibration errors on the efficacy of foreground mitigation strategies. We use an end-to-end pipeline $\textsc{21cmE2E}$ to simulate a realistic sky model and telescope configuration within the 138-146 MHz frequency range and perform a detailed power spectrum analysis across several threshold levels of the gain calibration error. We introduce a hybrid mitigation technique that combines the foreground removal techniques, Gaussian process regression and principal component analysis, with foreground avoidance. Our results indicate that recovery of the \HI\ signal within 2$\sigma$ is possible for calibration gain error of $\le 1\%$ with minimal loss of power spectrum sensitivity over the scale range $0.05\le k\le 0.5$ Mpc${}^{-1}$. We find that gain calibration errors beyond this threshold lead to signal suppression on large scales due to the loss of spectral smoothness of the residual foreground. In effect, this work offers a comparative assessment of three foreground mitigation strategies, removal, avoidance, and a hybrid approach, in the context of future SKA1-Low AA* observations.

29 + 1 pages, 15 figures, 2 tables; accepted for publication in JCAP. Comments and suggestions are welcome

References in corpus (67)

• SciPy 1.0--Fundamental Algorithms for Scientific Computing in Python
• Array Programming with NumPy
• emcee: The MCMC Hammer
• The Astropy Project: Building an inclusive, open-science project and status of the v2.0 core package
• LOFAR: The LOw-Frequency ARray
• Planck 2018 results. I. Overview and the cosmological legacy of Planck
• Cosmology at Low Frequencies: The 21 cm Transition and the High-Redshift Universe
• An absorption profile centred at 78 megahertz in the sky-averaged spectrum
• 21-cm cosmology
• WSClean: an implementation of a fast, generic wide-field imager for radio astronomy
• 21cmFAST: A Fast, Semi-Numerical Simulation of the High-Redshift 21-cm Signal
• Hydrogen Epoch of Reionization Array (HERA)
• Cosmological Parameter Estimation Using 21 cm Radiation from the Epoch of Reionization
• Bright Source Subtraction Requirements For Redshifted 21 cm Measurements
• What Next-Generation 21 cm Power Spectrum Measurements Can Teach Us About the Epoch of Reionization
• Science with the Murchison Widefield Array
• Four Fundamental Foreground Power Spectrum Shapes for 21 cm Cosmology Observations
• Improved upper limits on the 21-cm signal power spectrum of neutral hydrogen at $\mathbf{z}\approx 9.1$ from LOFAR
• Upper limits on the 21-cm Epoch of Reionization power spectrum from one night with LOFAR
• The Epoch of Reionization Window: I. Mathematical Formalism
• Toward Epoch of Reionization Measurements with Wide-Field Radio Observations
• The Epoch of Reionization Window: II. Statistical Methods for Foreground Wedge Reduction
• Comparison Of Reionization Models: Radiative Transfer Simulations And Approximate, Semi-Numeric Models
• The impact of point source subtraction residuals on 21 cm Epoch of Reionization estimation
• Calibration Requirements for Detecting the 21 cm Epoch of Reionization Power Spectrum and Implications for the SKA
• Improved Constraints on the 21 cm EoR Power Spectrum and the X-Ray Heating of the IGM with HERA Phase I Observations
• Foreground Removal using FastICA: A Showcase of LOFAR-EoR
• The Baryon Acoustic Oscillation Broadband and Broad-beam Array: Design Overview and Sensitivity Forecasts
• On using visibility correlations to probe the HI distribution from the dark ages to the present epoch I: Formalism and the expected signal
• The Cosmic Dawn and Epoch of Reionization with the Square Kilometre Array
• Blind foreground subtraction for intensity mapping experiments
• 21cmFAST v3: A Python-integrated C code forgenerating 3D realizations of the cosmic 21cm signal
• Realistic Simulations of the Galactic Polarized Foreground: Consequences for 21-cm Reionization Detection Experiments
• The Tiered Radio Extragalactic Continuum Simulation (T-RECS)
• The Scale of the Problem : Recovering Images of Reionization with GMCA
• Statistical 21-cm Signal Separation via Gaussian Process Regression Analysis
• The Impact of Modeling Errors on Interferometer Calibration for 21 cm Power Spectra
• First Limits on the 21 cm Power Spectrum during the Epoch of X-ray heating
• Mitigating Internal Instrument Coupling for 21 cm Cosmology I: Temporal and Spectral Modeling in Simulations
• Understanding the Diversity of 21 cm Cosmology Analyses
• Spectral calibration requirements of radio interferometers for Epoch of Reionisation science with the SKA
• Comparing Foreground Removal Techniques for Recovery of the LOFAR-EoR 21cm Power Spectrum
• Gaussian Process Foreground Subtraction and Power Spectrum Estimation for 21 cm Cosmology
• Polarized Redundant-Baseline Calibration for 21 cm Cosmology Without Adding Spectral Structure
• The Bias and Uncertainty of Redundant and Sky-Based Calibration under Realistic Sky and Telescope Conditions
• Foreground removal for Square Kilometre Array observations of the Epoch of Reionization with the Correlated Component Analysis
• Improved 21 cm Epoch Of Reionization Power Spectrum Measurements with a Hybrid Foreground Subtraction and Avoidance Technique
• Detailed study of ELAIS N1 field with the uGMRT -- II. Source Properties and Spectral Variation Of Foreground Power Spectrum from 300-500 MHz Observations
• Gaussian Process Regression for foreground removal in HI intensity mapping experiments
• The foreground transfer function for HI intensity mapping signal reconstruction: MeerKLASS and precision cosmology applications
• Detection of Signals from Cosmic Reionization using Radio Interferometric Signal Processing
• Foreground modelling via Gaussian process regression: an application to HERA data
• New EoR Power Spectrum Limits From MWA Phase II Using the Delay Spectrum Method and Novel Systematic Rejection
• Deeper multi-redshift upper limits on the Epoch of Reionization 21-cm signal power spectrum from LOFAR between z=8.3 and z=10.1
• Spectral performance of SKA Log-periodic Antennas I: Mitigating spectral artefacts in SKA1-LOW 21-cm cosmology experiments
• First multi-redshift limits on post-Epoch of Reionization (post-EoR) 21 cm signal from z = 1.96 - 3.58 using uGMRT
• Detailed study of the ELAIS N1 field with the uGMRT - I. Characterizing the 325 MHz foreground for redshifted 21 cm observations
• The Impact of Beam Variations on Power Spectrum Estimation for 21-cm Cosmology I: Simulations of Foreground Contamination for HERA
• A Bayesian analysis of redshifted 21-cm HI signal and foregrounds: Simulations for LOFAR
• Observing the Reionization : Effect of Calibration and Position Errors on Realistic Observation Conditions
• 21cmSense v2: A modular, open-source 21cm sensitivity calculator
• Detecting the HI Power Spectrum in the Post-Reionization Universe with SKA-Low
• Impact of instrument and data characteristics in the interferometric reconstruction of the 21 cm power spectrum
• RHINO: A large horn antenna for detecting the 21cm global signal
• Ionospheric effect on the synthetic Epoch of Reionization observations with the SKA1-Low
• Synthetic Observations with the Square Kilometre Array (SKA) -- development towards an end-to-end pipeline
• Impact of Calibration and Position Errors on Astrophysical Parameters of the HI 21cm Signal