Non-parametric foreground subtraction for 21cm epoch of reionization experiments

Abstract

An obstacle to the detection of redshifted 21cm emission from the epoch of reionization (EoR) is the presence of foregrounds which exceed the cosmological signal in intensity by orders of magnitude. We argue that in principle it would be better to fit the foregrounds non-parametrically - allowing the data to determine their shape - rather than selecting some functional form in advance and then fitting its parameters. Non-parametric fits often suffer from other problems, however. We discuss these before suggesting a non-parametric method, Wp smoothing, which seems to avoid some of them. After outlining the principles of Wp smoothing we describe an algorithm used to implement it. We then apply Wp smoothing to a synthetic data cube for the LOFAR EoR experiment. The performance of Wp smoothing, measured by the extent to which it is able to recover the variance of the cosmological signal and to which it avoids leakage of power from the foregrounds, is compared to that of a parametric fit, and to another non-parametric method (smoothing splines). We find that Wp smoothing is superior to smoothing splines for our application, and is competitive with parametric methods even though in the latter case we may choose the functional form of the fit with advance knowledge of the simulated foregrounds. Finally, we discuss how the quality of the fit is affected by the frequency resolution and range, by the characteristics of the cosmological signal and by edge effects.

15 pages, 12 figures; lengthened and two figures added, to match version accepted by MNRAS

References in corpus (21)

• Cosmological Parameter Estimation Using 21 cm Radiation from the Epoch of Reionization
• 21 Centimeter Fluctuations from Cosmic Gas at High Redshifts
• Radio observational constraints on Galactic 3D-emission models
• Multifrequency analysis of 21 cm fluctuations from the Era of Reionization
• Foreground simulations for the LOFAR - Epoch of Reionization Experiment
• Toward Epoch of Reionization Measurements with Wide-Field Radio Observations
• Fossil HII Regions: Self-Limiting Star Formation at High Redshift
• Radio Foregrounds for the 21cm Tomography of the Neutral Intergalactic Medium at High Redshifts
• Simulating Cosmic Reionization at Large Scales II: the 21-cm Emission Features and Statistical Signals
• Statistical Probes of Reionization With 21 cm Tomography
• Foreground Contamination in Interferometric Measurements of the Redshifted 21 cm Power Spectrum
• Twenty-one centimeter tomography with foregrounds
• Improving Foreground Subtraction in Statistical Observations of 21 cm Emission from the Epoch of Reionization
• Fast Large-Scale Reionization Simulations
• Will point sources spoil 21 cm tomography?
• De-contamination of cosmological 21-cm maps
• Time-evolution of ionization and heating around first stars and miniquasars
• Biased Reionisation and Non-Gaussianity in Redshifted 21cm Intensity Maps of the Reionisation Epoch
• Detection and extraction of signals from the epoch of reionization using higher order one-point statistics
• Current models of the observable consequences of cosmic reionization and their detectability
• Constraints on Fundamental Cosmological Parameters with Upcoming Redshifted 21 cm Observations

Cited by in corpus (92)

• Reionization and Cosmology with 21 cm Fluctuations
• Bright Source Subtraction Requirements For Redshifted 21 cm Measurements
• Reionization and the Cosmic Dawn with the Square Kilometre Array
• Upper limits on the 21-cm Epoch of Reionization power spectrum from one night with LOFAR
• The Epoch of Reionization Window: I. Mathematical Formalism
• PAPER-64 Constraints on Reionization: The 21cm Power Spectrum at z=8.4
• Data Analysis for Precision 21 cm Cosmology
• The Epoch of Reionization Window: II. Statistical Methods for Foreground Wedge Reduction
• Overcoming real-world obstacles in 21 cm power spectrum estimation: A method demonstration and results from early Murchison Widefield Array data
• The GMRT-EoR Experiment: A new upper limit on the neutral hydrogen power spectrum at z~8.6
• A Method for 21cm Power Spectrum Estimation in the Presence of Foregrounds
• Foreground Removal using FastICA: A Showcase of LOFAR-EoR
• Initial deep LOFAR observations of Epoch of Reionization windows: I. The North Celestial Pole
• Realistic Simulations of the Galactic Polarized Foreground: Consequences for 21-cm Reionization Detection Experiments
• The Scale of the Problem : Recovering Images of Reionization with GMCA
• The redshifted 21-cm signal in the EDGES low-band spectrum
• Statistical 21-cm Signal Separation via Gaussian Process Regression Analysis
• The Epoch of Reionization
• Foregrounds for observations of the cosmological 21 cm line: II. Westerbork observations of the fields around 3C196 and the North Celestial Pole
• Characterizing Foreground for redshifted 21-cm radiation: 150 MHz GMRT observations
• Systematic biases in low frequency radio interferometric data due to calibration: the LOFAR EoR case
• Power spectrum extraction for redshifted 21-cm epoch of reionization experiments: the LOFAR case
• Constraining the intergalactic medium at $z\approx$ 9.1 using LOFAR Epoch of Reionization observations
• How well can we measure and understand foregrounds with 21 cm experiments?
• The effect of foreground subtraction on cosmological measurements from Intensity Mapping
• A 189 MHz, 2400 square degree polarization survey with the Murchison Widefield Array 32-element prototype
• The Fundamental Multi-Baseline Mode-Mixing Foreground in 21 cm EoR Observations
• Probing reionization with LOFAR using 21-cm redshift space distortions
• Initial LOFAR observations of Epoch of Reionization windows: II. Diffuse polarized emission in the ELAIS-N1 field
• Chromatic effects in the 21 cm global signal from the cosmic dawn
• Global 21cm signal experiments: A designer's guide
• Improved foreground removal in GMRT 610 MHz observations towards redshifted 21-cm tomography
• A Fast Method for Power Spectrum and Foreground Analysis for 21 cm Cosmology
• The Murchison Widefield Array 21 cm Power Spectrum Analysis Methodology
• Constraining the epoch of reionization with the variance statistic: simulations of the LOFAR case
• The impact of interference excision on 21-cm Epoch of Reionization power spectrum analyses
• Constraining the state of the intergalactic medium during the Epoch of Reionization using MWA 21-cm signal observations
• Comparing Foreground Removal Techniques for Recovery of the LOFAR-EoR 21cm Power Spectrum
• A Foreground Masking Strategy for [CII] Intensity Mapping Experiments Using Galaxies Selected by Stellar Mass and Redshift
• Gaussian Process Foreground Subtraction and Power Spectrum Estimation for 21 cm Cosmology
• Spherical Harmonic Analyses of Intensity Mapping Power Spectra
• Imaging neutral hydrogen on large-scales during the Epoch of Reionization with LOFAR
• Separating the EoR Signal with a Convolutional Denoising Autoencoder: A Deep-learning-based Method
• Foreground removal for Square Kilometre Array observations of the Epoch of Reionization with the Correlated Component Analysis
• Subtraction of point sources from interferometric radio images through an algebraic forward modeling scheme
• 21SSD: a public database of simulated 21-cm signals from the epoch of reionization
• Prospects of observing a quasar HII region during the Epoch of Reionization with redshifted 21cm
• Light cone anisotropy in 21 cm signal from the epoch of reionization
• The 21-cm Line as a Probe of Reionization
• Radio astronomy with the Lunar Lander: opening up the last unexplored frequency regime
• Predictions for the 21cm-galaxy cross-power spectrum observable with LOFAR and Subaru
• Detection of Signals from Cosmic Reionization using Radio Interferometric Signal Processing
• Bayesian semi-blind component separation for foreground removal in interferometric 21-cm observations
• Signatures of clumpy dark matter in the global 21 cm background signal
• Contamination of the Epoch of Reionization power spectrum in the presence of foregrounds
• The impact of non-Gaussianity on the error covariance for observations of the Epoch of Reionization 21-cm power spectrum
• Low Frequency Imaging of Fields at High Galactic Latitude with the Murchison Widefield Array 32-Element Prototype
• Foreground modelling via Gaussian process regression: an application to HERA data
• Cross-correlation Study between the Cosmological 21-cm Signal and the kinetic Sunyaev-Zel'dovich effect
• Predictions for measuring the 21-cm multi-frequency angular power spectrum using SKA-Low
• Prospects for detecting the 326.5 MHz redshifted 21 cm HI signal with the Ooty Radio Telescope (ORT)
• Subtraction of Bright Point Sources from Synthesis Images of the Epoch of Reionization
• Deconvolving the Wedge: Maximum-Likelihood Power Spectra via Spherical-Wave Visibility Modeling
• Exploring the Cosmic Reionization Epoch in Frequency Space: An Improved Approach to Remove the Foreground in 21 cm Tomography
• Probing patchy reionization through tau-21cm correlation statistics
• Distinctive rings in the 21 cm signal of the epoch of reionization
• Probing large scale filaments with HI and ${}^3$HeII
• Deep learning approach for identification of HII regions during reionization in 21-cm observations -- II. foreground contamination
• The Epoch of Reionization 21-cm Bispectrum: The impact of light-cone effects and detectability
• The BINGO Project V: Further steps in Component Separation and Bispectrum Analysis
• A Bayesian analysis of redshifted 21-cm HI signal and foregrounds: Simulations for LOFAR
• Extracting the 21-cm Power Spectrum and the reionization parameters from mock datasets using Artificial Neural Networks
• Delay Spectrum with Phase-Tracking Arrays: Extracting the HI power spectrum from the Epoch of Reionization
• Methods of Error Estimation for Delay Power Spectra in $21\text{cm}$ Cosmology
• A General Bayesian Framework to Account for Foreground Map Errors in Global 21-cm Experiments
• Radio Recombination Lines at Decametre Wavelengths: Prospects for the Future
• Identifying Ionized Regions in Noisy Redshifted 21 cm Data Sets
• Measuring the Redshift of Reionization with a Modest Array of Low-Frequency Dipoles
• Extracting the Global 21-cm signal from Cosmic Dawn and Epoch of Reionization in the presence of Foreground and Ionosphere
• Constraints on the state of the IGM at $z\sim 8-10$ using redshifted 21-cm observations with LOFAR
• The Application of Continuous Wavelet Transform Based Foreground Subtraction Method in 21 cm Sky Surveys
• Degree-Scale Galactic Radio Emission at 122 MHz around the North Celestial Pole with LOFAR-AARTFAAC
• Non-Gaussianity of diffuse Galactic synchrotron emission at 408 MHz
• The 21cm Power Spectrum and the Shapes of Non-Gaussianity
• Probing the intergalactic medium during the Epoch of Reionization using 21-cm signal power spectra
• Measuring the reionization 21 cm fluctuations using clustering wedges
• A Comparative Analysis To Deal With Missing Spectral Information Caused By RFI In Cosmological HI 21CM Observations
• Testing synchrotron models and frequency resolution in BINGO 21 cm simulated maps using GNILC
• Influence of synchrotron self-absorption on the 21cm experiments
• Deep learning approach for identification of HII regions during reionization in 21-cm observations -- III. image recovery
• Probing the Epoch of Reionization using synergies of line intensity mapping
• Imaging and Modeling Data from the Hydrogen Epoch of Reionization Array