Adam P. Beardsley
A5032516498- Radio Astronomy Observations and Technology
- Astrophysics and Cosmic Phenomena
- Antenna Design and Optimization
- Radio Wave Propagation Studies
- Galaxies: Formation, Evolution, Phenomena
- Astronomy and Astrophysical Research
- Particle Accelerators and Free-Electron Lasers
- Superconducting and THz Device Technology
- Electromagnetic Compatibility and Measurements
- Gamma-ray bursts and supernovae
- Astronomical Observations and Instrumentation
- Soil Moisture and Remote Sensing
- Pulsars and Gravitational Waves Research
- Millimeter-Wave Propagation and Modeling
- History and Developments in Astronomy
- Gyrotron and Vacuum Electronics Research
- Advanced SAR Imaging Techniques
- Computational Physics and Python Applications
- Microwave Engineering and Waveguides
- Astrophysical Phenomena and Observations
- Pulsed Power Technology Applications
- Advanced Optical Sensing Technologies
- Venous Thromboembolism Diagnosis and Management
- Optical measurement and interference techniques
- Scientific Research and Discoveries
Arizona State University
2016-2025
Winona State University
2021-2025
University of Virginia
2023-2024
University of Virginia Hospital
2023
University of Arizona
2018
University of Washington
2012-2017
Seattle University
2013
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,...
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....
The discovery of the first electromagnetic counterpart to a gravitational wave signal has generated follow-up observations by over 50 facilities world-wide, ushering in new era multi-messenger astronomy. In this paper, we present event GW170817 and its SSS17a/DLT17ck (IAU label AT2017gfo) 14 Australian telescopes partner observatories as part Australian-based Australian-led research programs. We report early- late-time multi-wavelength observations, including optical imaging spectroscopy,...
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...
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 We describe the motivation and design details of ‘Phase II’ upgrade Murchison Widefield Array radio telescope. The expansion doubles to 256 number antenna tiles deployed in array. new enhance capabilities several key science areas. Seventy-two are a regular configuration near existing array core. These surface brightness sensitivity will improve ability estimate slope Epoch Reionisation power spectrum by factor ∼3.5. remaining 56 on long baselines, doubling maximum baseline...
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 confirm our recent prediction of the "pitchfork" foreground signature in power spectra high-redshift 21 cm measurements where interferometer is sensitive to large-scale structure on all baselines. This due inherent response a wide-field instrument and characterized by enhanced from emission Fourier modes adjacent those considered be most cosmological H i signal. In paper, many signatures simulation that predicted this feature were validated against Murchison Widefield Array (MWA) data,...
We present the 21 cm power spectrum analysis approach of Murchison Widefield Array Epoch Reionization project. In this paper, we compare outputs multiple pipelines for purpose validating statistical limits cosmological hydrogen at redshifts between 6 and 12. Multiple, independent, data calibration reduction are used to make on a fiducial night data. Comparing imaging stages highlights differences in calibration, foreground subtraction calculation. The spectra found using these different...
Experiments that pursue detection of signals from the Epoch Reionization (EoR) are relying on spectral smoothness source spectra at low frequencies. This article empirically explores effect foreground EoR experiments by measuring high-resolution full-polarization for 586 brightest unresolved sources in one Murchison Widefield Array (MWA) fields using 45 h observation. A novel peeling scheme is used to subtract 2500 visibilities with ionospheric and beam corrections, resulting deepest,...
We present a study of internal reflection and cross coupling systematics in Phase I the Hydrogen Epoch Reionization Array (HERA). In companion paper, we outlined mathematical formalism for such presented algorithms modeling removing them from data. this work, apply these techniques to data HERA's first observing season as method demonstration. The show evidence that, without removal, would hinder detection 21 cm power spectrum targeted EoR line-of-sight modes range 0.2 < k_parallel 0.5\ h^-1...
ABSTRACT Observations in the lowest Murchison Widefield Array (MWA) band between 75 and 100 MHz have potential to constrain distribution of neutral hydrogen intergalactic medium at redshift ∼13–17. Using 15 h MWA data, we analyse systematics this such as radio-frequency interference (RFI), ionospheric wide field effects. By updating position point sources, mitigate direction-independent calibration error due offsets. Our strategy is optimized for frequency bands by reducing number...
Using the final 128 antenna locations of Murchison Widefield Array (MWA), we calculate its sensitivity to Epoch Reionization (EoR) power spectrum red- shifted 21 cm emission for a fiducial model and provide tools any model. Our calculation takes into account synthesis rotation, chro- matic asymmetrical baseline effects, excludes modes that will be contaminated by foreground subtraction. For model, MWA capable 14{\sigma} detection EoR signal with one full season observation on two fields (900...
21 cm power spectrum observations have the potential to revolutionize our understanding of Epoch Reionization and Dark Energy, but require extraordinarily precise data analysis methods separate cosmological signal from astrophysical instrumental contaminants. This challenge has led a diversity proposed analyses, including delay spectra, imaging m-mode analysis, numerous others. approach is strength, also confusion within community about whether insights gleaned by one group are applicable...
We present deep polarimetric observations at 154 MHz with the Murchison Widefield Array (MWA), covering 625 deg^2 centered on RA=0 h, Dec=-27 deg. The sensitivity available in our allows an in-band, frequency-dependent analysis of polarized structure for first time long wavelengths. Our suggests that structures are dominated by intrinsic emission but may also have a foreground Faraday screen component. At these wavelengths, compactness MWA baseline distribution provides excellent snapshot to...
In this paper we present observations, simulations, and analysis demonstrating the direct connection between location of foreground emission on sky its in cosmological power spectra from interferometric redshifted 21 cm experiments. We begin with a heuristic formalism for understanding mapping coordinates into cylindrically averaged measurements used by experiments, focus effects instrument beam response associated sidelobes. then demonstrate analyzing both simulated observed data Murchison...