B. J. Hazelton
A5080933124- Radio Astronomy Observations and Technology
- Astrophysics and Cosmic Phenomena
- Radio Wave Propagation Studies
- Antenna Design and Optimization
- Galaxies: Formation, Evolution, Phenomena
- Astronomy and Astrophysical Research
- Lightning and Electromagnetic Phenomena
- Millimeter-Wave Propagation and Modeling
- Particle Accelerators and Free-Electron Lasers
- Astronomical Observations and Instrumentation
- Ionosphere and magnetosphere dynamics
- Electromagnetic Compatibility and Measurements
- Gamma-ray bursts and supernovae
- Soil Moisture and Remote Sensing
- History and Developments in Astronomy
- Superconducting and THz Device Technology
- Pulsars and Gravitational Waves Research
- GNSS positioning and interference
- Advanced Optical Sensing Technologies
- Computational Physics and Python Applications
- Solar and Space Plasma Dynamics
- Microwave Engineering and Waveguides
- Electromagnetic Compatibility and Noise Suppression
- Optical Systems and Laser Technology
- Optical measurement and interference techniques
University of Washington
2016-2025
Arizona State University
2016-2024
University of California, Los Angeles
2024
Software (Spain)
2019
Seattle University
2012-2018
The University of Sydney
2015
Netherlands Institute for Radio Astronomy
2015
John Wiley & Sons (United States)
2015
Charles River Laboratories (Netherlands)
2015
University of California, Santa Cruz
2009-2010
The Murchison Widefield Array (MWA) is one of three Square Kilometre Precursor telescopes and located at the Radio-astronomy Observatory in Shire mid-west Western Australia, a location chosen for its extremely low levels radio frequency interference. MWA operates frequencies, 80-300 MHz, with processed bandwidth 30.72 MHz both linear polarisations, consists 128 aperture arrays (known as tiles) distributed over ~3 km diameter area. Novel hybrid hardware/software correlation real-time imaging...
Astronomical wide-field imaging of interferometric radio data is computationally expensive, especially for the large volumes created by modern non-coplanar many-element arrays. We present a new imager that uses w-stacking algorithm and can make use w-snapshot algorithm. The performance dependences casa's w-projection our are analysed analytical functions derived describe required computing cost both imagers. On from Murchison Widefield Array, we find method to be an order magnitude faster...
The Hydrogen Epoch of Reionization Array (HERA) is a staged experiment to measure 21 cm emission from the primordial intergalactic medium (IGM) throughout cosmic reionization ($z=6-12$), and explore earlier epochs our Cosmic Dawn ($z\sim30$). During these epochs, early stars black holes heated ionized IGM, introducing fluctuations in emission. HERA designed characterize evolution power spectrum constrain timing morphology reionization, properties first galaxies, large-scale structure,...
Abstract Using the Murchison Widefield Array (MWA), low-frequency Square Kilometre precursor located in Western Australia, we have completed GaLactic and Extragalactic All-sky MWA (GLEAM) survey, present resulting extragalactic catalogue, utilizing first year of observations. The catalogue covers 24 831 square degrees, over declinations south +30° Galactic latitudes outside 10° plane, excluding some areas such as Magellanic Clouds. It contains 307 455 radio sources with 20 separate flux...
Abstract Significant new opportunities for astrophysics and cosmology have been identified at low radio frequencies. The Murchison Widefield Array is the first telescope in southern hemisphere designed specifically to explore low-frequency astronomical sky between 80 300 MHz with arcminute angular resolution high survey efficiency. will enable advances along four key science themes, including searching redshifted 21-cm emission from EoR early Universe; Galactic extragalactic all-sky surveys;...
Contamination from instrumental effects interacting with bright astrophysical sources is the primary impediment to measuring Epoch of Reionization (EoR) and Baryon Acoustic Oscillations (BAO) 21 cm power spectra—an effect called mode mixing. In this paper, we identify four fundamental spectrum shapes produced by mixing that will affect all upcoming observations. We are able, for first time, explain wedge-like structure seen in advanced simulations forecast shape an "EoR window" mostly free...
The Murchison Widefield Array (MWA) has collected hundreds of hours Epoch Reionization (EoR) data and now faces the challenge overcoming foreground systematic contamination to reduce a cosmological measurement. We introduce several novel analysis techniques such as cable reflection calibration, hyper-resolution gridding kernels, diffuse model subtraction, quality control methods. Each change pipeline is tested against two dimensional power spectrum figure merit demonstrate improvement....
We compute the spherically-averaged power spectrum from four seasons of data obtained for Epoch Reionisation (EoR) project observed with Murchison Widefield Array (MWA). measure EoR over $k= 0.07-3.0~h$Mpc$^{-1}$ at redshifts $z=6.5-8.7$. The largest aggregation 110 hours on EoR0 high-band (3,340 observations), yields a lowest measurement (43~mK)$^2$ = 1.8$\times$10$^3$ mK$^2$ $k$=0.14~$h$Mpc$^{-1}$ and $z=6.5$ (2$\sigma$ thermal noise plus sample variance). Using Real-Time System to...
Abstract We report upper limits on the Epoch of Reionization 21 cm power spectrum at redshifts 7.9 and 10.4 with 18 nights data (∼36 hr integration) from Phase I Hydrogen Array (HERA). The show evidence for systematics that can be largely suppressed systematic models down to a dynamic range ∼10 9 respect peak foreground power. This yields 95% confidence limit <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msubsup> <mml:mrow> <mml:mi...
Abstract Recently, the Hydrogen Epoch of Reionization Array (HERA) has produced experiment’s first upper limits on power spectrum 21 cm fluctuations at z ∼ 8 and 10. Here, we use several independent theoretical models to infer constraints intergalactic medium (IGM) galaxies during epoch reionization from these limits. We find that IGM must have been heated above adiabatic-cooling threshold by 8, uncertainties about ionization radio background. Combining HERA with complementary observations...
Abstract We report the most sensitive upper limits to date on 21 cm epoch of reionization power spectrum using 94 nights observing with Phase I Hydrogen Epoch Reionization Array (HERA). Using similar analysis techniques as in previously reported limits, we find at 95% confidence that Δ 2 ( k = 0.34 h Mpc −1 ) ≤ 457 mK z 7.9 and 0.36 3496 10.4, an improvement by a factor 2.1 2.6, respectively. These are mostly consistent thermal noise over wide range after our data quality cuts, despite...
We describe a new low-frequency wideband radio survey of the southern sky. Observations covering 72-231MHz and Declinations south +30° have been performed with Murchison Widefield Array "extended" Phase I configuration over 2018-2020 will be processed to form data products including continuum polarisation images mosaics, multi-frequency catalogues, transient search data, ionospheric measurements. From pilot field described in this work, we publish an initial release 1,447 deg2 4 h≤ RA≤ 13 h,...
21 cm epoch of reionization (EoR) observations promise to transform our understanding galaxy formation, but these are impossible without unprecedented levels instrument calibration. We present end-to-end simulations a full EoR power spectrum (PS) analysis including all the major components real data processing pipeline: models astrophysical foregrounds and signal, frequency-dependent effects, sky-based antenna calibration, PS analysis. This study reveals that traditional per-frequency...
In this paper we explore for the first time relative magnitudes of three fundamental sources uncertainty, namely, foreground contamination, thermal noise and sample variance in detecting HI power spectrum from Epoch Reionization (EoR). We derive limits on sensitivity a Fourier synthesis telescope to detect EoR based its array configuration statistical representation images made by instrument. use Murchison Widefield Array (MWA) our studies. Using unified framework estimating signal...
The Murchison Widefield Array (MWA) is a new low-frequency interferometric radio telescope built in Western Australia at one of the locations future Square Kilometre (SKA). We describe automated radio-frequency interference (RFI) detection strategy implemented for MWA, which based on AOFlagger platform, and present 72-231-MHz RFI statistics from 10 observing nights. removes 1.1% data. digital TV (DTV) observed 3% time due to occasional ionospheric or atmospheric propagation. After excision,...
Measurements of 21 cm Epoch Reionization (EoR) structure are subject to systematics originating from both the analysis and observation conditions. Using 2013 data Murchison Widefield Array (MWA), we show importance mitigating sources contamination. A direct comparison between results Beardsley et al. 2016 our updated demonstrates new precision techniques, lowering by a factor 2.8 in power. We then further lower excising observations contaminated ultra-faint RFI, reducing an additional 3.8...
The separation of the faint cosmological background signal from bright astrophysical foregrounds remains one most daunting challenges mapping high-redshift intergalactic medium with redshifted 21 cm line neutral hydrogen. Advances in and modeling diffuse point source have improved subtraction accuracy, but no scheme is perfect. Precisely quantifying errors error correlations due to missubtracted allows for both rigorous analysis power spectrum maximal isolation "EoR window" foreground...
Detection of the cosmological neutral hydrogen signal from Epoch Reionization, and estimation its basic physical parameters, is principal scientific aim many current low-frequency radio telescopes. Here we describe Cosmological HI Power Spectrum Estimator (CHIPS), an algorithm developed implemented with data Murchison Widefield Array (MWA), to compute two-dimensional spherically-averaged power spectrum brightness temperature fluctuations. The motivations for CHIPS are application realistic...
Detection of 21~cm emission HI from the epoch reionization, at redshifts z>6, is limited primarily by foreground emission. We investigate signatures wide-field measurements and an all-sky model using delay spectrum technique that maps to object locations through signal delays between antenna pairs. demonstrate interferometric are inherently sensitive all scales, including largest angular owing nature measurements. These effects generic observations but shapes impact their amplitudes...
We present first results from radio observations with the Murchison Widefield Array seeking to constrain power spectrum of 21 cm brightness temperature fluctuations between redshifts 11.6 and 17.9 (113 75 MHz). 3 h were conducted over two nights significantly different levels ionospheric activity. use these data assess impact systematic errors at low frequency, including ionosphere radio-frequency interference, on a measurement. find that after 1–3 integration presented here, our...
Abstract The compact configuration of Phase II the Murchison Widefield Array (MWA) consists both a redundant subarray and pseudo-random baselines, offering unique opportunities to perform sky-model interferometric calibration. highly hexagonal cores give improved power spectrum sensitivity. In this paper, we present analysis nearly 40 hr data targeting one MWA’s epoch reionization (EoR) fields observed in 2016. We use techniques presented Barry et al. several additional developed for work,...
Abstract This paper presents the design and deployment of Hydrogen Epoch Reionization Array (HERA) phase II system. HERA is designed as a staged experiment targeting 21 cm emission measurements Reionization. First results from I array are published early 2022, system nearing completion. We describe discuss progress on commissioning future upgrades. As designated Square Kilometre pathfinder instrument, we also show number “case studies” that investigate systematics seen while system, which...
We present a summary of data from the Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI) terrestrial gamma ray flash (TGF) catalog. describe RHESSI search algorithm and discuss its limitations due to design emphasis on cleanliness rather than completeness. This has identified 820 TGFs between March 2002 February 2008. Radiation damage detectors resulted in decreased sensitivity after early 2006 corresponding decrease number years 2006–2008. Prior this, average rate occurrence was...
The primary challenge for experiments measuring the neutral hydrogen power spectrum from epoch of reionization (EoR) is mode-mixing effects, where foregrounds very bright astrophysical sources interact with instrument to contaminate EoR signal. In this paper, we identify a new type mode mixing that occurs when measurements non-identical baselines are combined increased sensitivity. This multi-baseline effect dominates in our simulations and can window, an area Fourier space previously...
ABSTRACT We introduce the Fast Holographic Deconvolution method for analyzing interferometric radio data. Our new is an extension of A-projection/software-holography/forward modeling analysis techniques and shares their precision deconvolution wide-field polarimetry, while being significantly faster than current implementations that use full direction-dependent antenna gains. Using data from MWA 32 prototype, we demonstrate effectiveness our algorithm. may be particularly important upcoming...