Robust statistics toward detection of the 21 cm signal from the Epoch of Reionisation

Abstract

We explore methods for robust estimation of the 21 cm signal from the Epoch of Reionisation (EoR). A Kernel Density Estimator (KDE) is introduced for measuring the spatial temperature fluctuation power spectrum from the EoR. The KDE estimates the underlying probability distribution function of fluctuations as a function of spatial scale, and contains different systematic biases and errors to the typical approach to estimating the fluctuation power spectrum. Extraction of histograms of visibilities allows moments analysis to be used to discriminate foregrounds from 21 cm signal and thermal noise. We use the information available in the histograms, along with the statistical dis-similarity of foregrounds from two independent observing fields, to robustly separate foregrounds from cosmological signal, while making no assumptions about the Gaussianity of the signal. Using two independent observing fields to robustly discriminate signal from foregrounds is crucial for the analysis presented in this paper. We apply the techniques to 13 hours of Murchison Widefield Array (MWA) EoR data over two observing fields. We compare the output to that obtained with a comparative power spectrum estimation method, and demonstrate the reduced foreground contamination using this approach. Using the second moment obtained directly from the KDE distribution functions yields a factor of 2-3 improvement in power for k < 0.3hMpc^{-1} compared with a matched delay space power estimator, while weighting data by additional statistics does not offer significant improvement beyond that available for thermal noise-only weights.

arXiv comment19 pages, 18 figures, accepted for publication in MNRAS

References in corpus (28)

• LOFAR: The LOw-Frequency ARray
• Cosmology at Low Frequencies: The 21 cm Transition and the High-Redshift Universe
• The Murchison Widefield Array: the Square Kilometre Array Precursor at low radio frequencies
• 21cmFAST: A Fast, Semi-Numerical Simulation of the High-Redshift 21-cm Signal
• Hydrogen Epoch of Reionization Array (HERA)
• The Precision Array for Probing the Epoch of Reionization: 8 Station Results
• Bright Source Subtraction Requirements For Redshifted 21 cm Measurements
• Science with the Murchison Widefield Array
• Upper limits on the 21-cm Epoch of Reionization power spectrum from one night with LOFAR
• PAPER-64 Constraints on Reionization: The 21cm Power Spectrum at z=8.4
• The Phase II Murchison Widefield Array: Design Overview
• Imaging the Epoch of Reionization: limitations from foreground confusion and imaging algorithms
• Searches for Anisotropies in the Arrival Directions of the Highest Energy Cosmic Rays Detected by the Pierre Auger Observatory
• The impact of point source subtraction residuals on 21 cm Epoch of Reionization estimation
• The GMRT-EoR Experiment: A new upper limit on the neutral hydrogen power spectrum at z~8.6
• Real-Time Calibration of the Murchison Widefield Array
• First Season MWA EoR Power Spectrum Results at Redshift 7
• Foregrounds in Wide-Field Redshifted 21 cm Power Spectra
• CHIPS: The Cosmological HI Power Spectrum Estimator
• Quantifying the non-Gaussianity in the EoR 21-cm signal through bispectrum
• Estimating Long GRB Jet Opening Angles and Rest-Frame Energetics
• Characterisation of the ionosphere above the Murchison Radio Observatory using the Murchison Widefield Array
• The Murchison Widefield Array 21 cm Power Spectrum Analysis Methodology
• Biased Reionisation and Non-Gaussianity in Redshifted 21cm Intensity Maps of the Reionisation Epoch
• The Hercules-Lyra Association revisited New age estimation and multiplicity study
• Diagnosing the magnetic field structure of a coronal cavity observed during the 2017 total solar eclipse
• The angular power spectrum measurement of the Galactic synchrotron emission in two fields of the TGSS survey
• An Improved Statistical Point-Source Foreground Model for the Epoch of Reionization

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• Data Analysis for Precision 21 cm Cosmology
• Detection of Cosmic Structures using the Bispectrum Phase. II. First Results from Application to Cosmic Reionization Using the Hydrogen Epoch of Reionization Array
• A flexible method for estimating luminosity functions via Kernel Density Estimation
• Two-point statistics without bins: A continuous-function generalization of the correlation function estimator for large-scale structure