Validation of EDGES Low-Band Antenna Beam Model

Abstract

The response of the antenna is a source of uncertainty in measurements with the Experiment to Detect the Global EoR Signature (EDGES). We aim to validate the beam model of the low-band (50-100 MHz) dipole antenna with comparisons between models and against data. We find that simulations of a simplified model of the antenna over an infinite perfectly conducting ground plane are, with one exception, robust to changes of numerical electromagnetic solver code or algorithm. For simulations of the antenna with the actual finite ground plane and realistic soil properties, we find that two out of three numerical solvers agree well. Applying our analysis pipeline to a simulated driftscan observation from an early EDGES low-band instrument that had a 10 m $\times$ 10 m ground plane, we find residual levels after fitting and removing a five-term foreground model to data binned in Local Sidereal Time (LST) average about 250 mK with $\pm$40 mK variation between numerical solvers. A similar analysis of the primary 30 m $\times$ 30 m sawtooth ground plane reduced the LST-averaged residuals to about 90 mK with $\pm$10 mK between the two viable solvers. More broadly we show that larger ground planes generally perform better than smaller ground planes. Simulated data have a power which is within 4$\%$ of real observations, a limitation of net accuracy of the sky and beam models. We observe that residual spectral structures after foreground model fits match qualitatively between simulated data and observations, suggesting that the frequency dependence of the beam is reasonably represented by the models. We find that soil conductivity of 0.02 Sm${}^{-1}$ and relative permittivity of 3.5 yield good agreement between simulated spectra and observations. This is consistent with the soil properties reported by Sutinjo et al. (2015) for the Murchison Radio-astronomy Observatory, where EDGES is located.

arXiv comment19 pages, 17 figures

References in corpus (42)

• Planck 2015 results. XIII. Cosmological parameters
• Nine-Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Cosmological Parameter Results
• LOFAR: The LOw-Frequency ARray
• The Murchison Widefield Array: the Square Kilometre Array Precursor at low radio frequencies
• An absorption profile centred at 78 megahertz in the sky-averaged spectrum
• Observational constraints on Cosmic Reionization
• Hydrogen Epoch of Reionization Array (HERA)
• Model-independent evidence in favor of an end to reionization by z~6
• Science with the Murchison Widefield Array
• PAPER-64 Constraints on Reionization: The 21cm Power Spectrum at z=8.4
• Concerns about Modelling of the EDGES Data
• A lower limit of dz > 0.06 for the duration of the reionization epoch
• The GMRT-EoR Experiment: A new upper limit on the neutral hydrogen power spectrum at z~8.6
• Cosmic microwave background constraints on the duration and timing of reionization from the South Pole Telescope
• First Results from the Lyman Alpha Galaxies in the Epoch of Reionization (LAGER) Survey: Cosmological Reionization at z ~ 7
• Testing for calibration systematics in the EDGES low-band data using Bayesian model selection
• BIGHORNS - Broadband Instrument for Global HydrOgen ReioNisation Signal
• All-sky Galactic radiation at 45 MHz and spectral index between 45 and 408 MHz
• A Ground Plane Artifact that Induces an Absorption Profile in Averaged Spectra from Global 21-cm Measurements - with Possible Application to EDGES
• First results on the Epoch of Reionization from First Light with SARAS 2
• Bayesian constraints on the global 21-cm signal from the Cosmic Dawn
• The 21 cm Power Spectrum from the Cosmic Dawn: First Results from the OVRO-LWA
• Toward Empirical Constraints on the Global Redshifted 21 cm Brightness Temperature During the Epoch of Reionization
• Results from EDGES High-Band: I. Constraints on Phenomenological Models for the Global $21$ cm Signal
• SARAS 2: A Spectral Radiometer for probing Cosmic Dawn and the Epoch of Reionization through detection of the global 21 cm signal
• SARAS: a precision system for measurement of the Cosmic Radio Background and signatures from the Epoch of Reionization
• Calibration of the EDGES High-Band Receiver to Observe the Global 21-cm Signature from the Epoch of Reionization
• PAPER-64 Constraints On Reionization II: The Temperature Of The z=8.4 Intergalactic Medium
• Improved Measurement of the Spectral Index of the Diffuse Radio Background Between 90 and 190 MHz
• Characterization of a Low-Frequency Radio Astronomy Prototype Array in Western Australia
• Results from EDGES High-Band: III. New Constraints on Parameters of the Early Universe
• Beam calibration of radio telescopes with drones
• Spectral Index of the Diffuse Radio Background Between 50 and 100 MHz
• Measuring Phased-Array Antenna Beampatterns with High Dynamic Range for the Murchison Widefield Array using 137 MHz ORBCOMM Satellites
• Limits on Foreground Subtraction from Chromatic Beam Effects in Global Redshifted 21 cm Measurements
• Results from EDGES High-Band: II. Constraints on Parameters of Early Galaxies
• A Technique for Primary Beam Calibration of Drift-Scanning, Wide-Field Antenna Elements
• On the contamination of the global 21~cm signal from polarized foregrounds
• In situ measurement of MWA primary beam variation using ORBCOMM
• Radio Sources in the NCP Region Observed with the 21 Centimeter Array
• Absolute Calibration of Diffuse Radio Surveys at 45 and 150 MHz
• Holographic Beam Mapping of the CHIME Pathfinder Array

Cited by in corpus (24)

• First Results from HERA Phase I: Upper Limits on the Epoch of Reionization 21 cm Power Spectrum
• Improved Constraints on the 21 cm EoR Power Spectrum and the X-Ray Heating of the IGM with HERA Phase I Observations
• Mapper of the IGM spin temperature: instrument overview
• Antenna beam characterisation for the global 21cm experiment LEDA and its impact on signal model parameter reconstruction
• Informing antenna design for sky-averaged 21-cm experiments using a simulated Bayesian data analysis pipeline
• Lunar Orbit Measurement of Cosmic Dawn 21 cm Global Spectrum
• A Bayesian Calibration Framework for EDGES
• A Bayesian approach to modelling spectrometer data chromaticity corrected using beam factors -- I. Mathematical formalism
• Simulating the Detection of the Global 21 cm Signal with MIST for Different Models of the Soil and Beam Directivity
• Analytic approximations of scattering effects on beam chromaticity in 21-cm global experiments
• The effects of the antenna power pattern uncertainty within a global 21 cm experiment
• The EDGES measurement disfavors an excess radio background during the cosmic dawn
• RHINO: A large horn antenna for detecting the 21cm global signal
• Effects of model incompleteness on the drift-scan calibration of radio telescopes
• Direction-dependent effects on global 21-cm detection
• Optimization of Antenna Performance for Global 21-cm Observations and Verification Using Scaled Copies
• A Bayesian approach to modelling spectrometer data chromaticity corrected using beam factors -- II. Model priors and posterior odds
• Low-Frequency Radio Recombination Lines Away From the Inner Galactic Plane
• EDGES of the dark forest: A new absorption window into the composite dark matter and large scale structure
• The Bayesian Global Sky Model (B-GSM): Validation of a Data Driven Bayesian Simultaneous Component Separation and Calibration Algorithm for EoR Foreground Modelling
• Using the antenna impedance to estimate soil electrical parameters for the MIST global 21-cm experiment
• The impact of lunar topography on the 21-cm power spectrum for grid-based arrays : Insights for the Dark-ages EXplorer (DEX)
• Implications of the cosmological 21-cm absorption profile for high-redshift star formation and deep JWST surveys
• An SBC-based controller and processor for the laboratory model of PRATUSH Digital Receiver