Absolute Calibration Strategies for the Hydrogen Epoch of Reionization Array and Their Impact on the 21 cm Power Spectrum

Abstract

We discuss absolute calibration strategies for Phase I of the Hydrogen Epoch of Reionization Array (HERA), which aims to measure the cosmological 21 cm signal from the Epoch of Reionization (EoR). HERA is a drift-scan array with a 10 degree wide field of view, meaning bright, well-characterized point source transits are scarce. This, combined with HERA's redundant sampling of the uv plane and the modest angular resolution of the Phase I instrument, make traditional sky-based and self-calibration techniques difficult to implement with high dynamic range. Nonetheless, in this work we demonstrate calibration for HERA using point source catalogues and electromagnetic simulations of its primary beam. We show that unmodeled diffuse flux and instrumental contaminants can corrupt the gain solutions, and present a gain smoothing approach for mitigating their impact on the 21 cm power spectrum. We also demonstrate a hybrid sky and redundant calibration scheme and compare it to pure sky-based calibration, showing only a marginal improvement to the gain solutions at intermediate delay scales. Our work suggests that the HERA Phase I system can be well-calibrated for a foreground-avoidance power spectrum estimator by applying direction-independent gains with a small set of degrees of freedom across the frequency and time axes.

Accepted to ApJ

References in corpus (17)

• GaLactic and Extragalactic All-sky Murchison Widefield Array (GLEAM) survey I: A low-frequency extragalactic catalogue
• The non-coplanar baselines effect in radio interferometry: The W-Projection algorithm
• The Epoch of Reionization Window: I. Mathematical Formalism
• The Very Large Array Low-frequency Sky Survey Redux (VLSSr)
• First Season MWA EoR Power Spectrum Results at Redshift 7
• Correcting direction-dependent gains in the deconvolution of radio interferometric images
• Improving the Epoch of Reionization Power Spectrum Results from Murchison Widefield Array Season 1 Observations
• Fast Holographic Deconvolution: a new technique for precision radio interferometry
• MITEoR: A Scalable Interferometer for Precision 21 cm Cosmology
• Multi-redshift limits on the 21cm power spectrum from PAPER
• Mitigating Internal Instrument Coupling for 21 cm Cosmology I: Temporal and Spectral Modeling in Simulations
• Mitigating Internal Instrument Coupling II: A Method Demonstration with the Hydrogen Epoch of Reionization Array
• The challenges of low-frequency radio polarimetry: lessons from the Murchison Widefield Array
• Modelling of the Spectral Energy Distribution of Fornax A: Leptonic and Hadronic Production of High Energy Emission from the Radio Lobes
• The FHD/$\mathbf{\epsilon }$ppsilon Epoch of Reionization Power Spectrum Pipeline
• Constraining Polarized Foregrounds for EOR Experiments II: Polarization Leakage Simulations in the Avoidance Scheme
• Fundamental uncertainty levels of 21cm power spectra from a delay analysis

Cited by in corpus (20)

• Improved Constraints on the 21 cm EoR Power Spectrum and the X-Ray Heating of the IGM with HERA Phase I Observations
• Hydrogen Epoch of Reionization Array (HERA) Phase II Deployment and Commissioning
• Foreground modelling via Gaussian process regression: an application to HERA data
• Detection of Cosmic Structures using the Bispectrum Phase. II. First Results from Application to Cosmic Reionization Using the Hydrogen Epoch of Reionization Array
• Measuring HERA's primary beam in-situ: methodology and first results
• The Impact of Beam Variations on Power Spectrum Estimation for 21-cm Cosmology I: Simulations of Foreground Contamination for HERA
• Observing the Reionization : Effect of Calibration and Position Errors on Realistic Observation Conditions
• On the use of temporal filtering for mitigating galactic synchrotron calibration bias in 21 cm reionization observations
• A Bayesian approach to high fidelity interferometric calibration II: demonstration with simulated data
• Impact of instrument and data characteristics in the interferometric reconstruction of the 21 cm power spectrum
• Post-reionization HI 21-cm signal: A probe of negative cosmological constant
• Direct Optimal Mapping for 21cm Cosmology: A Demonstration with the Hydrogen Epoch of Reionization Array
• Spectral modelling of Cygnus A between 110 and 250 MHz. Impact on the LOFAR 21-cm signal power spectrum
• Delay-Weighted Calibration: Precision Calibration for 21 cm Cosmology with Resilience to Sky Model Error
• A Differentiable, End-to-End Forward Model for 21 cm Cosmology: Estimating the Foreground, Instrument, and Signal Joint Posterior
• Probing the Epoch of Reionization using synergies of line intensity mapping
• Simulations of primary beam effects on the cosmic bispectrum phase observed with the Hydrogen Epoch of Reionization Array
• Exploring One-point Statistics in HERA Phase I Data: Effects of Foregrounds and Systematics on Measuring One-Point Statistics
• A Bayesian approach to high fidelity interferometric calibration I: mathematical formalism
• Removing systematics-induced 21-cm foreground residuals by cross-correlating filtered data