Matthew Kolopanis
A5046932423- Radio Astronomy Observations and Technology
- Astrophysics and Cosmic Phenomena
- Antenna Design and Optimization
- Radio Wave Propagation Studies
- Astronomy and Astrophysical Research
- Electromagnetic Compatibility and Measurements
- Galaxies: Formation, Evolution, Phenomena
- Soil Moisture and Remote Sensing
- Astronomical Observations and Instrumentation
- Millimeter-Wave Propagation and Modeling
- Superconducting and THz Device Technology
- Particle Accelerators and Free-Electron Lasers
- Scientific Research and Discoveries
- Computational Physics and Python Applications
- Gyrotron and Vacuum Electronics Research
- Spacecraft and Cryogenic Technologies
- Microwave Engineering and Waveguides
- Advanced Wireless Communication Techniques
- Cosmology and Gravitation Theories
- Spacecraft Design and Technology
- Space Exploration and Technology
- Adaptive optics and wavefront sensing
- Pulsed Power Technology Applications
- Optical measurement and interference techniques
- Advanced Optical Sensing Technologies
Arizona State University
2013-2025
University of Pennsylvania
2024
University of California, Berkeley
2023
Software (Spain)
2019
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...
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...
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...
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 We present limits on the 21 cm power spectrum from Epoch of Reionization using data 64 antenna configuration Donald C. Backer Precision Array for Probing (PAPER) analyzed through a pipeline independent previous PAPER analyses. Previously reported results have been found to contain significant signal loss. Several lossy steps pipelines not included in this analysis, namely delay-based foreground filtering, optimal fringe-rate and empirical covariance-based estimators. Steps that...
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...
ABSTRACT In 21-cm cosmology, precision calibration is key to the separation of neutral hydrogen signal from very bright but spectrally smooth astrophysical foregrounds. The Hydrogen Epoch Reionization Array (HERA), an interferometer specialized for cosmology and now under construction in South Africa, was designed be largely calibrated using self-consistency repeated measurements same interferometric modes. This technique, known as redundant-baseline resolves most internal degrees freedom...
Abstract We discuss absolute calibration strategies for Phase I of the Hydrogen Epoch Reionization Array (HERA), which aims to measure cosmological 21 cm signal from Reionization. HERA is a drift-scan array with 10° wide field view, meaning bright, well-characterized point-source transits are scarce. This, combined HERA’s redundant sampling uv plane and modest angular resolution instrument, make traditional sky-based self-calibration techniques difficult implement high dynamic range....
Radio Frequency Interference (RFI) is an ever-present limiting factor among radio telescopes even in the most remote observing locations. When looking to retain maximum amount of sensitivity and reduce contamination for Epoch Reionization studies, identification removal RFI especially important. In addition improved identification, we must also take into account computational efficiency RFI-Identification algorithm as interferometer arrays such Hydrogen Array grow larger number receivers. To...
ABSTRACT The detection of the Epoch Reionization (EoR) delay power spectrum using a ‘foreground avoidance method’ highly depends on instrument chromaticity. systematic effects induced by radio telescope spread foreground signal in domain, which contaminates EoR window theoretically observable. Applied to Hydrogen Array (HERA), this paper combines detailed electromagnetic and electrical simulations order model chromatic instrument, quantify its frequency time responses. In particular,...
We describe the validation of HERA Phase I software pipeline by a series modular tests, building up to an end-to-end simulation. The philosophy this approach is validate and algorithms used in upper limit analysis on wholly synthetic data satisfying assumptions that analysis, not addressing whether actual meet these assumptions. discuss organization approach, specific tests performed, construction simulations. explicitly limitations scope current simulation effort. With mock visibility...
Abstract The precise characterization and mitigation of systematic effects is one the biggest roadblocks impeding detection fluctuations cosmological 21 cm signals. Missing data in radio experiments, often due to frequency interference (RFI), pose a particular challenge power spectrum analysis as this could lead ringing bright foreground modes Fourier space, heavily contaminating Here we show that problem missing becomes even more arduous presence effects. Using realistic numerical...
ABSTRACT Detection of the faint 21 cm line emission from Cosmic Dawn and Epoch Reionization will require not only exquisite control over instrumental calibration systematics to achieve necessary dynamic range observations but also validation analysis techniques demonstrate their statistical properties signal loss characteristics. A key ingredient in achieving this is ability perform high-fidelity simulations kinds data that are produced by large, many-element, radio interferometric arrays...
Abstract Observations of the 21 cm Epoch Reionization signal are dominated by Galactic and extragalactic foregrounds. The need for foreground removal has led to development two main techniques, often referred as “foreground avoidance” subtraction.” Avoidance is associated with filtering foregrounds in Fourier space, while subtraction uses an explicit model that removed. Using 1088 hr data from 64-element PAPER array, we demonstrate a prior delay-space results modest but measurable...
Data simulations are essential to the progress of low-frequency radio telescope arrays such as HERA, MWA, and LOFAR, for future instruments like SKA.Simulated datasets used verify analysis pipelines, provide models sky-based calibration, test effects design choices environmental factors.Existing simulators (CASA, OSKAR, FHD, PRISim, et al.) make simplifying assumptions reduce computational demand evaluating measurement equation, compromising accuracy speed.This can lead unexpected numerical...
The key challenge in the observation of redshifted 21-cm signal from cosmic reionization is its separation much brighter foreground emission. Such relies on different spectral properties two components, although, real life, intrinsic spectrum often corrupted by instrumental response, inducing systematic effects that can further jeopardize measurement signal. In this paper, we use Gaussian Process Regression to model both emission and systematics $\sim 2$ hours data Hydrogen Epoch...
Radio Frequency Interference (RFI) is one of the systematic challenges preventing 21cm interferometric instruments from detecting Epoch Reionization. To mitigate effects RFI on data analysis pipelines, numerous inpaint techniques have been developed to restore corrupted data. We examine qualitative and quantitative errors introduced into visibilities power spectrum due inpainting. perform our simulated as well real Hydrogen Reionization Array (HERA) Phase 1 upper limits. also introduce a...
We present an analysis of Epoch Reionization data from Phase II the Murchison Widefield Array using \texttt{simpleDS} delay spectrum pipeline. Prior work analyzed same observations FHD/$\varepsilon$ppsilon imaging pipeline, and so represents first time that both principal types 21 cm cosmology power estimation approaches have been applied to set. Our limits on amplitude span a range in $k$ space $|k| < 1~h_{100}{\rm Mpc}^{-1}$ with lowest measurement $\Delta^2(k) \leq$ $4.58\times10^3$...
Characterizing the epoch of reionization (EoR) at z≳6 via redshifted 21 cm line neutral Hydrogen (H i) is critical to modern astrophysics and cosmology, thus a key science goal many current planned low-frequency radio telescopes. The primary challenge detecting this signal overwhelmingly bright foreground emission these frequencies, placing stringent requirements on knowledge instruments inaccuracies in analyses. Results from experiments have largely been limited not by thermal sensitivity...
ABSTRACT Current attempts to measure the 21 cm power spectrum of neutral hydrogen during epoch reionization (EoR) are limited by systematics that produce measured upper limits above both thermal noise and expected cosmological signal. These arise from a combination observational, instrumental, analysis effects. In order further understand mitigate these effects, it is instructive explore different aspects existing data sets. One such aspect choice observing field. To date, MWA EoR...
Interferometric experiments designed to detect the highly redshifted 21-cm signal from neutral hydrogen are producing increasingly stringent constraints on power spectrum, but some k-modes remain systematics-dominated. Mutual coupling is a major systematic that must be overcome in order signal, and simulations reproduce effects seen data can guide strategies for mitigating mutual coupling. In this paper, we analyse 12 nights of Hydrogen Epoch Reionization Array compare against include...
The 21 cm transition from neutral Hydrogen promises to be the best observational probe of Epoch Reionisation (EoR). This has led construction low-frequency radio interferometric arrays, such as Reionization Array (HERA), aimed at systematically mapping this emission for first time. Precision calibration, however, is a requirement in observations. Due spatial compactness HERA, array prone effects mutual coupling, which inevitably lead non-smooth calibration errors that contaminate data. When...
Foreground power dominates the measurements of interferometers that seek a statistical detection highly-redshifted HI emission from Epoch Reionization (EoR). The chromaticity instrument creates boundary in Fourier transform frequency (proportional to $k_\parallel$) between spectrally smooth emission, characteristic strong synchrotron foreground (the "wedge"), and structured EoR "EoR window"). Faraday rotation can inject spectral structure into otherwise polarized which through effects or...