Search Results - "Robnett, James"
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Hydrogen Epoch of Reionization Array (HERA)
Published in Publications of the Astronomical Society of the Pacific (01-04-2017)“…The Hydrogen Epoch of Reionization Array (HERA) is a staged experiment to measure 21 cm emission from the primordial intergalactic medium (IGM) throughout…”
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HERA Phase I Limits on the Cosmic 21 cm Signal: Constraints on Astrophysics and Cosmology during the Epoch of Reionization
Published in The Astrophysical journal (01-01-2022)“…Abstract Recently, the Hydrogen Epoch of Reionization Array (HERA) has produced the experiment’s first upper limits on the power spectrum of 21 cm fluctuations…”
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Improved Constraints on the 21 cm EoR Power Spectrum and the X-Ray Heating of the IGM with HERA Phase I Observations
Published in The Astrophysical journal (01-03-2023)“…Abstract We report the most sensitive upper limits to date on the 21 cm epoch of reionization power spectrum using 94 nights of observing with Phase I of the…”
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Mitigating Internal Instrument Coupling for 21 cm Cosmology. II. A Method Demonstration with the Hydrogen Epoch of Reionization Array
Published in The Astrophysical journal (10-01-2020)“…We present a study of internal reflection and cross-coupling systematics in Phase I of the Hydrogen Epoch of Reionization Array (HERA). In a companion paper,…”
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Redundant-baseline calibration of the hydrogen epoch of reionization array
Published in Monthly notices of the Royal Astronomical Society (01-12-2020)“…ABSTRACT In 21-cm cosmology, precision calibration is key to the separation of the neutral hydrogen signal from very bright but spectrally smooth astrophysical…”
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Absolute Calibration Strategies for the Hydrogen Epoch of Reionization Array and Their Impact on the 21 cm Power Spectrum
Published in The Astrophysical journal (20-02-2020)“…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…”
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Understanding the HERA Phase I receiver system with simulations and its impact on the detectability of the EoR delay power spectrum
Published in Monthly notices of the Royal Astronomical Society (01-01-2021)“…ABSTRACT The detection of the Epoch of Reionization (EoR) delay power spectrum using a ‘foreground avoidance method’ highly depends on the instrument…”
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Foreground modelling via Gaussian process regression: an application to HERA data
Published in Monthly notices of the Royal Astronomical Society (01-07-2020)“…ABSTRACT The key challenge in the observation of the redshifted 21-cm signal from cosmic reionization is its separation from the much brighter foreground…”
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Optimizing sparse RFI prediction using deep learning
Published in Monthly notices of the Royal Astronomical Society (11-09-2019)“…ABSTRACT Radio frequency interference (RFI) is an ever-present limiting factor among radio telescopes even in the most remote observing locations. When looking…”
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Validation of the HERA Phase I Epoch of Reionization 21 cm Power Spectrum Software Pipeline
Published in The Astrophysical journal (01-01-2022)“…Abstract We describe the validation of the HERA Phase I software pipeline by a series of modular tests, building up to an end-to-end simulation. The philosophy…”
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A demonstration of the effect of fringe-rate filtering in the hydrogen epoch of reionization array delay power spectrum pipeline
Published in Monthly notices of the Royal Astronomical Society (12-11-2024)“…Abstract Radio interferometers targeting the 21cm brightness temperature fluctuations at high redshift are subject to systematic effects that operate over a…”
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Bayesian estimation of cross-coupling and reflection systematics in 21cm array visibility data
Published in Monthly notices of the Royal Astronomical Society (15-10-2024)“…Abstract Observations with radio arrays that target the 21-cm signal originating from the early Universe suffer from a variety of systematic effects. An…”
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Characterization of inpaint residuals in interferometric measurements of the epoch of reionization
Published in Monthly notices of the Royal Astronomical Society (22-02-2023)“…ABSTRACT To mitigate the effects of Radio Frequency Interference (RFI) on the data analysis pipelines of 21 cm interferometric instruments, numerous inpaint…”
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The HERA-19 Commissioning Array: Direction-dependent Effects
Published in The Astrophysical journal (01-09-2019)“…Foreground power dominates the measurements of interferometers that seek a statistical detection of highly-redshifted H i emission from the Epoch of…”
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Impact of instrument and data characteristics in the interferometric reconstruction of the 21 cm power spectrum
Published in Monthly notices of the Royal Astronomical Society (01-03-2023)“…ABSTRACT Combining the visibilities measured by an interferometer to form a cosmological power spectrum is a complicated process. In a delay-based analysis,…”
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Search for the Epoch of Reionization with HERA: upper limits on the closure phase delay power spectrum
Published in Monthly notices of the Royal Astronomical Society (04-07-2023)“…ABSTRACT Radio interferometers aiming to measure the power spectrum of the redshifted 21 cm line during the Epoch of Reionization (EoR) need to achieve an…”
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Direct Optimal Mapping for 21 cm Cosmology: A Demonstration with the Hydrogen Epoch of Reionization Array
Published in The Astrophysical journal (01-10-2022)“…Abstract Motivated by the desire for wide-field images with well-defined statistical properties for 21 cm cosmology, we implement an optimal mapping pipeline…”
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Bayesian jackknife tests with a small number of subsets: application to HERA 21 cm power spectrum upper limits
Published in Monthly notices of the Royal Astronomical Society (01-02-2023)“…ABSTRACT We present a Bayesian jackknife test for assessing the probability that a data set contains biased subsets, and, if so, which of the subsets are…”
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Effects of model incompleteness on the drift-scan calibration of radio telescopes
Published in Monthly notices of the Royal Astronomical Society (01-09-2021)“…ABSTRACT Precision calibration poses challenges to experiments probing the redshifted 21-cm signal of neutral hydrogen from the Cosmic Dawn and Epoch of…”
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Measuring HERA's Primary Beam in Situ: Methodology and First Results
Published in The Astrophysical journal (01-07-2020)“…The central challenge in 21 cm cosmology is isolating the cosmological signal from bright foregrounds. Many separation techniques rely on the accurate…”
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