Search Results - "Kern, Nicholas"
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Gaussian process foreground subtraction and power spectrum estimation for 21 cm cosmology
Published in Monthly notices of the Royal Astronomical Society (01-02-2021)“…ABSTRACT One of the primary challenges in enabling the scientific potential of 21 cm intensity mapping at the epoch of reionization (EoR) is the separation of…”
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Emulating Simulations of Cosmic Dawn for 21 cm Power Spectrum Constraints on Cosmology, Reionization, and X-Ray Heating
Published in The Astrophysical journal (10-10-2017)“…Current and upcoming radio interferometric experiments are aiming to make a statistical characterization of the high-redshift 21 cm fluctuation signal spanning…”
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Mitigating Internal Instrument Coupling for 21 cm Cosmology. I. Temporal and Spectral Modeling in Simulations
Published in The Astrophysical journal (20-10-2019)“…We study the behavior of internal signal chain reflections and antenna cross coupling as systematics for 21 cm cosmological surveys. We outline the mathematics…”
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Results from EDGES High-band. II. Constraints on Parameters of Early Galaxies
Published in The Astrophysical journal (10-08-2018)“…We use the sky-average spectrum measured by EDGES High-band (90-190 MHz) to constrain parameters of early galaxies independent of the absorption feature at 78…”
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The Impact of Beam Variations on Power Spectrum Estimation for 21 cm Cosmology. I. Simulations of Foreground Contamination for HERA
Published in The Astrophysical journal (01-12-2022)“…Abstract Detecting cosmological signals from the Epoch of Reionization (EoR) requires high-precision calibration to isolate the cosmological signals from…”
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Polarized redundant-baseline calibration for 21 cm cosmology without adding spectral structure
Published in Monthly notices of the Royal Astronomical Society (01-07-2018)“…Abstract 21 cm cosmology is a promising new probe of the evolution of visible matter in our universe, especially during the poorly constrained Cosmic Dawn and…”
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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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The Impact of Beam Variations on Power Spectrum Estimation for 21 cm Cosmology. II. Mitigation of Foreground Systematics for HERA
Published in The Astrophysical journal (01-08-2023)“…Abstract One key challenge in detecting a 21 cm cosmological signal at z > 6 is to separate the cosmological signal from foreground emission. This can be…”
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Quantifying EoR delay spectrum contamination from diffuse radio emission
Published in Monthly notices of the Royal Astronomical Society (21-05-2020)“…ABSTRACT The 21 cm hyperfine transition of neutral hydrogen offers a promising probe of the large-scale structure of the universe before and during the Epoch…”
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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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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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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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