Fundamental uncertainty levels of 21cm power spectra from a delay analysis

Abstract

Several experimental efforts are underway to measure the power spectrum of 21cm fluctuations from the Epoch of Reionization (EoR) using low-frequency radio interferometers. Experiments like the Hydrogen Epoch of Reionization Array (HERA) and Murchison Widefield Array Phase II (MWA) feature highly-redundant antenna layouts, building sensitivity through redundant measurements of the same angular Fourier modes, at the expense of diminished UV coverage. This strategy limits the numbers of independent samples of each power spectrum mode, thereby increasing the effect of sample variance on the final power spectrum uncertainty. To better quantify this effect, we measure the sample variance of a delay-transform based power spectrum estimator, using both analytic calculations and simulations of flat-spectrum EoR-like signals. We find that for the shortest baselines in HERA, the sample variance can reach as high as 20%, and up to 30% for the wider fields-of-view of the MWA. Combining estimates from all the baselines in a HERA- or MWA-like 37 element redundant hexagonal array can lower the variance to $1-3$% for some Fourier modes. These results have important implications for observing and analysis strategies, and suggest that sample variance can be non-negligible when constraining EoR model parameters from upcoming 21cm data.

arXiv comment15 pages, 11 figures

References in corpus (48)

• Astropy: A Community Python Package for Astronomy
• The Astropy Project: Building an inclusive, open-science project and status of the v2.0 core package
• HEALPix -- a Framework for High Resolution Discretization, and Fast Analysis of Data Distributed on the Sphere
• Cosmology at Low Frequencies: The 21 cm Transition and the High-Redshift Universe
• 21cmFAST: A Fast, Semi-Numerical Simulation of the High-Redshift 21-cm Signal
• Hydrogen Epoch of Reionization Array (HERA)
• Reionization and Cosmology with 21 cm Fluctuations
• Cosmological Parameter Estimation Using 21 cm Radiation from the Epoch of Reionization
• The Precision Array for Probing the Epoch of Reionization: 8 Station Results
• 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
• Reionization and the Cosmic Dawn with the Square Kilometre Array
• A simulation calibrated limit on the HI power spectrum from the GMRT Epoch of Reionization experiment
• A Per-Baseline, Delay-Spectrum Technique for Accessing the 21cm Cosmic Reionization Signature
• Science with the Murchison Widefield Array
• Four Fundamental Foreground Power Spectrum Shapes for 21 cm Cosmology Observations
• Upper limits on the 21-cm Epoch of Reionization power spectrum from one night with LOFAR
• New Limits on 21cm EoR From PAPER-32 Consistent with an X-Ray Heated IGM at z=7.7
• Foreground simulations for the LOFAR - Epoch of Reionization Experiment
• PAPER-64 Constraints on Reionization: The 21cm Power Spectrum at z=8.4
• 21CMMC: an MCMC analysis tool enabling astrophysical parameter studies of the cosmic 21 cm signal
• A Sensitivity and Array-Configuration Study for Measuring the Power Spectrum of 21cm Emission from Reionization
• Evolution of the 21 cm signal throughout cosmic history
• The GMRT-EoR Experiment: A new upper limit on the neutral hydrogen power spectrum at z~8.6
• First Season MWA EoR Power Spectrum Results at Redshift 7
• Detecting the Rise and Fall of 21 cm Fluctuations with the Murchison Widefield Array
• The Baryon Acoustic Oscillation Broadband and Broad-beam Array: Design Overview and Sensitivity Forecasts
• A study of fundamental limitations to statistical detection of redshifted HI from the epoch of reionization
• Foregrounds in Wide-Field Redshifted 21 cm Power Spectra
• Initial deep LOFAR observations of Epoch of Reionization windows: I. The North Celestial Pole
• Precision Calibration of Radio Interferometers Using Redundant Baselines
• Empirical Covariance Modeling for 21 cm Power Spectrum Estimation: A Method Demonstration and New Limits from Early Murchison Widefield Array 128-Tile Data
• Foregrounds for observations of the cosmological 21 cm line: II. Westerbork observations of the fields around 3C196 and the North Celestial Pole
• Deep learning from 21-cm tomography of the Cosmic Dawn and Reionization
• The Fundamental Multi-Baseline Mode-Mixing Foreground in 21 cm EoR Observations
• Calibration of Low-Frequency, Wide-Field Radio Interferometers Using Delay/Delay-Rate Filtering
• The Importance of Wide-field Foreground Removal for 21 cm Cosmology: A Demonstration With Early MWA Epoch of Reionization Observations
• Emulation of reionization simulations for Bayesian inference of astrophysics parameters using neural networks
• Redundant Array Configurations for 21 cm Cosmology
• Characterizing Signal Loss in the 21 cm Reionization Power Spectrum: A Revised Study of PAPER-64
• The EoR Sensitivity of the Murchison Widefield Array
• The Hydrogen Epoch of Reionization Array Dish I: Beam Pattern Measurements and Science Implications
• The effect of non-Gaussianity on error predictions for the Epoch of Reionization (EoR) 21-cm power spectrum
• The 154 MHz radio sky observed by the Murchison Widefield Array: noise, confusion and first source count analyses
• In situ measurement of MWA primary beam variation using ORBCOMM
• The impact of non-Gaussianity on the error covariance for observations of the Epoch of Reionization 21-cm power spectrum
• Comparison of observing modes for statistical estimation of the 21cm signal from the Epoch of Reionisation
• Unlocking Sensitivity for Visibility-based Estimators of the 21 cm Reionization Power Spectrum

Cited by in corpus (14)

• Data Analysis for Precision 21 cm Cosmology
• Mitigating Internal Instrument Coupling II: A Method Demonstration with the Hydrogen Epoch of Reionization Array
• Mitigating Internal Instrument Coupling for 21 cm Cosmology I: Temporal and Spectral Modeling in Simulations
• DAYENU: A Simple Filter of Smooth Foregrounds for Intensity Mapping Power Spectra
• Absolute Calibration Strategies for the Hydrogen Epoch of Reionization Array and Their Impact on the 21 cm Power Spectrum
• Foreground modelling via Gaussian process regression: an application to HERA data
• Validation of the HERA Phase I Epoch of Reionization 21 cm Power Spectrum Software Pipeline
• Detection of Cosmic Structures using the Bispectrum Phase. II. First Results from Application to Cosmic Reionization Using the Hydrogen Epoch of Reionization Array
• Methods of Error Estimation for Delay Power Spectra in $21\text{cm}$ Cosmology
• Quantifying EoR delay spectrum contamination from diffuse radio emission
• A Bayesian approach to high fidelity interferometric calibration II: demonstration with simulated data
• All Sky Modelling Requirements for Bayesian 21 cm Power Spectrum Estimation with BayesEoR
• Detecting 21 cm EoR Signal using Drift Scans: Correlation of Time-ordered Visibilities
• Reionization Parameter Inference from 3D Minkowski Functionals of the 21 cm Signals