Aaron R. Parsons
A5088100194- Radio Astronomy Observations and Technology
- Astrophysics and Cosmic Phenomena
- Antenna Design and Optimization
- Radio Wave Propagation Studies
- Superconducting and THz Device Technology
- Astronomy and Astrophysical Research
- Galaxies: Formation, Evolution, Phenomena
- Particle Accelerators and Free-Electron Lasers
- Electromagnetic Compatibility and Measurements
- Millimeter-Wave Propagation and Modeling
- Astronomical Observations and Instrumentation
- Soil Moisture and Remote Sensing
- History and Developments in Astronomy
- Gamma-ray bursts and supernovae
- Cosmology and Gravitation Theories
- Particle accelerators and beam dynamics
- Scientific Research and Discoveries
- Space Science and Extraterrestrial Life
- Planetary Science and Exploration
- Advanced Wireless Communication Techniques
- Particle Detector Development and Performance
- Digital Filter Design and Implementation
- Microwave Engineering and Waveguides
- Gyrotron and Vacuum Electronics Research
- Adaptive optics and wavefront sensing
University of California, Berkeley
2016-2025
Massachusetts Institute of Technology
2023
National Radio Astronomy Observatory
2020-2021
Berkeley College
2019
University of Groningen
2015
University of Puerto Rico at Arecibo
2010
GVD Corporation (United States)
1961
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,...
We are developing the Precision Array for Probing Epoch of Re-ionization (PAPER) to detect 21 cm emission from early universe, when first stars and galaxies were forming. describe overall experiment strategy architecture summarize two PAPER deployments: a four-antenna array in low radio frequency interference (RFI) environment Western Australia an eight-antenna at prototyping site NRAO facilities near Green Bank, WV. From these activities we report on system performance, including primary...
A critical challenge in measuring the power spectrum of 21 cm emission from cosmic reionization is compensating for frequency dependence an interferometer's sampling pattern, which can cause smooth-spectrum foregrounds to appear unsmooth and degrade separation between target signal. In this paper, we present approach foreground removal that explicitly accounts dependence. We apply delay transformation introduced Parsons & Backer each baseline interferometer concentrate within bounds maximum...
In this paper, we report new limits on 21cm emission from cosmic reionization based a 135-day observing campaign with 64-element deployment of the Donald C. Backer Precision Array for Probing Epoch Reionization (PAPER) in South Africa. This work extends presented Parsons et al. (2014) more collecting area, longer period, improved redundancy-based calibration, optimal fringe-rate filtering, and power-spectral analysis using quadratic estimators. The result is $2\sigma$ upper limit...
The authors develop a rigorous and robust framework for data analysis, aimed at foreground reduction, in particular eliciting information from the 21 cm line, where noise can be considerably stronger than cosmological signal.
We present new constraints on the 21cm Epoch of Reionization (EoR) power spectrum derived from 3 months observing with a 32-antenna, dual-polarization deployment Donald C. Backer Precision Array for Probing (PAPER) in South Africa. In this paper, we demonstrate efficacy delay-spectrum approach to avoiding foregrounds, achieving over 8 orders magnitude foreground suppression (in $\textrm{mK}^2$). Combining procedure removing off-diagonal covariances arising instrumental systematics, achieve...
A number of experiments are currently working toward a measurement the 21 cm signal from epoch reionization (EoR). Whether or not these deliver detection cosmological emission, their limited sensitivity will prevent them providing detailed information about astrophysics reionization. In this work, we consider what types measurements be enabled by next generation larger EoR telescopes. To calculate type constraints that possible with such arrays, use simple models for instrument, foreground...
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 present new observations with the Precision Array for Probing Epoch of Reionization aim measuring properties foreground emission 21 cm epoch reionization (EoR) experiments at 150 MHz. focus on footprint foregrounds in cosmological Fourier space to understand which modes power spectrum will most likely be compromised by emission. These confirm predictions that can isolated a "wedge"-like region two-dimensional (k⊥, k∥)-space, creating window studies higher k∥ values. also find extends past...
Telescopes aiming to measure 21cm emission from the Epoch of Reionization must toe a careful line, balancing need for raw sensitivity against stringent calibration requirements removing bright foregrounds. It is unclear what optimal design achieving both these goals. Via pedagogical derivation an interferometer's response power spectrum reionization fluctuations, we show that even under optimistic scenarios, first-generation arrays will yield low-SNR detections, and different compact array...
For there to be a successful measurement of the 21 cm epoch reionization (EoR) power spectrum, it is crucial that strong foreground contaminants robustly suppressed. These foregrounds come from variety sources (such as Galactic synchrotron emission and extragalactic point sources), but almost all share property being spectrally smooth and, when viewed through chromatic response an interferometer, occupy signature ``wedge'' region in cylindrical...
The Collaboration for Astronomy Signal Processing and Electronics Research (CASPER) has been working a decade to reduce the time cost of designing, building deploying new digital radio-astronomy instruments. Today, CASPER open-source technology powers over 45 scientific instruments worldwide, is used by scientists engineers at dozens academic institutions. In this paper, we catalog current offerings collaboration, past present built users developers. We describe ongoing state software...
Concerted effort is currently ongoing to open up the Epoch of Reionization (z ∼15-6) for studies with IR and radio telescopes.Whereas detections have been made sources (Lyman-α emitters, quasars drop-outs) in this redshift regime relatively small fields view, no direct detection neutral hydrogen, via redshifted 21-cm line, has yet established.Such a expected coming years, surveys, could entire universe from z ∼6-200 astrophysical cosmological studies, opening not only Reionization, but also...
Abstract Current and upcoming radio interferometric experiments are aiming to make a statistical characterization of the high-redshift 21 cm fluctuation signal spanning hydrogen reionization X-ray heating epochs universe. However, connecting statistics underlying physical parameters is complicated by theoretical challenge modeling relevant physics at computational speeds quick enough enable exploration high-dimensional weakly constrained parameter space. In this work, we use machine learning...
Amongst standard model parameters that are constrained by cosmic microwave background (CMB) observations, the optical depth $τ$ stands out as a nuisance parameter. While provides some crude limits on reionization, it also degrades constraints other cosmological parameters. Here we explore how 21 cm cosmology---as direct probe of reionization---can be used to independently predict in an effort improve CMB parameter constraints. We develop two complementary schemes for doing so. The first uses...
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...
This work describes a new instrument optimized for detection of the neutral hydrogen 21cm power spectrum between redshifts 0.5-1.5: Baryon Acoustic Oscillation Broadband and Broad-beam (BAOBAB) Array. BAOBAB will build on efforts first generation experiments which are targeting signal from Epoch Reionization at z ~ 10. At 1, emission in self-shielded overdense halos also presents an accessible signal, since dominant, synchrotron foreground is considerably fainter than redshift The principle...
Experiments aimed at detecting highly-redshifted 21 cm emission from the epoch of reionization (EoR) are plagued by contamination foreground emission. A potentially important source contaminating foregrounds may be Faraday-rotated, polarized emission, which leaks into estimate intrinsically unpolarized EoR signal. While these foregrounds' intrinsic polarization not problematic, spectral structure introduced Faraday rotation could be. To better understand and characterize effects, we present...
ABSTRACT Realizing the potential of 21 cm tomography to statistically probe intergalactic medium before and during Epoch Reionization requires large telescopes precise control systematics. Next-generation are now being designed built meet these challenges, drawing lessons from first-generation experiments that showed benefits densely packed, highly redundant arrays—in which same mode on sky is sampled by many antenna pairs—for achieving high sensitivity, calibration, robust foreground...
The epoch of reionization power spectrum is expected to evolve strongly with redshift, and it this variation cosmic history that will allow us begin place constraints on the physics reionization. primary obstacle measurement EoR bright foreground emission. We present an analysis observations from Donald C. Backer Precision Array for Probing Epoch Reionization (PAPER) telescope which new limits HI over redshift range $7.5<z<10.5$, extending previously published single results cover full...
We present constraints on both the kinetic temperature of intergalactic medium (IGM) at z=8.4, and models for heating IGM high-redshift with X-ray emission from first collapsed objects. These are derived using a semi-analytic method to explore new measurements 21 cm power spectrum Donald C. Backer Precision Array Probing Epoch Reionization (PAPER), which were presented in companion paper, Ali et al. (2015). Twenty-one spectra amplitudes hundreds mK^2 can be generically produced if is...
Abstract The Epoch of Reionization (EoR) is an uncharted era in our universe’s history during which the birth first stars and galaxies led to ionization neutral hydrogen intergalactic medium. There are many experiments investigating EoR by tracing 21 cm line hydrogen. Because this signal very faint difficult isolate, it crucial develop analysis techniques that maximize sensitivity suppress contaminants data. It also imperative understand trade-offs between different methods their effects on...
ABSTRACT Unaccounted for systematics from foregrounds and instruments can severely limit the sensitivity of current experiments detecting redshifted 21 cm signals Epoch Reionization (EoR). Upcoming are faced with a challenge to deliver more collecting area per antenna element without degrading data systematics. This paper its companions show that dishes viable achieving this balance using Hydrogen Array (HERA) as an example. Here, we specifically identify spectral associated power pattern...