A5016091848- Radio Astronomy Observations and Technology
- Astrophysics and Cosmic Phenomena
- Precipitation Measurement and Analysis
- Superconducting and THz Device Technology
- Soil Moisture and Remote Sensing
- Galaxies: Formation, Evolution, Phenomena
- Antenna Design and Optimization
- Radio Wave Propagation Studies
- Planetary Science and Exploration
- Millimeter-Wave Propagation and Modeling
- Cellular Automata and Applications
- Computational Physics and Python Applications
- Space Science and Extraterrestrial Life
- Astro and Planetary Science
- Space exploration and regulation
- Astronomy and Astrophysical Research
- Adaptive optics and wavefront sensing
- Advanced Wireless Communication Techniques
- Speech and Audio Processing
- Microwave Engineering and Waveguides
Laboratory for Atmospheric and Space Physics
2020-2025
University of Colorado Boulder
2020-2025
Upcoming ground and space-based experiments may have sufficient accuracy to place significant constraints upon high-redshift star formation, Reionization, dark matter (DM) using the global 21-cm signal of intergalactic medium. In early universe, when relative abundance low-mass DM halos is important, measuring would on damping structure formation caused by having a higher relic velocity (warm matter, or WDM) than in cold (CDM). Such damping, however, can be mimicked altering efficiency (SFE)...
All 21-cm signal experiments rely on electronic receivers that affect the data via both multiplicative and additive biases through receiver's gain noise temperature. While attempt to remove these biases, residuals of their imperfect calibration techniques can still confuse extraction algorithms. In this paper, fourth final installment our pipeline series, we present a technique for fitting out receiver effects as efficiently possible. The fact global signal, which are multiplied in...
Abstract We present an investigation of the horizon and its effect on global 21 cm observations analysis. find that cannot be ignored when modeling low-frequency observations. Even if sky antenna beam are known exactly, forward models fully describe beam-weighted foreground component without accurate knowledge horizon. When fitting data to extract signal, a single time-averaged spectrum or independent multi-spectrum fits may able compensate for bias imposed by However, these types lack...
In order to characterize and model the beam-weighted foreground for global 21-cm signal experiments, we present a methodology generating basis eigenvectors that combines analytical observational models of both galactic spectral index sky brightness temperature with simulations beams having various angular dependencies pointings. Each combination creates unique foreground. By fit each using Singular Value Decomposition (SVD), examine effects varying components We find modelling an achromatic,...
The Lunar Surface Electromagnetics Explorer 'LuSEE Night' is a low frequency radio astronomy experiment that will be delivered to the farside of Moon by NASA Commercial Payload Services (CLPS) program in late 2025 or early 2026. payload system being developed jointly and US Department Energy (DOE) consists 4 channel, 50 MHz Nyquist baseband receiver 2 orthogonal $\sim$6m tip-to-tip electric dipole antennas. LuSEE Night enjoy standalone operations through lunar night, without electromagnetic...
Abstract We present a methodology for ensuring the robustness of our analysis pipeline in separating global 21 cm hydrogen cosmology signal from large systematics based on singular value decomposition (SVD) training sets. show how traditional goodness-of-fit metrics such as χ 2 statistic that assess fit to full data may not be able detect suboptimal extraction when it is alongside one or more additional components owing significant covariance between them. However, we find comparing number...
Abstract Although neural-network-based emulators enable efficient parameter estimation in 21 cm cosmology, the accuracy of such constraints is poorly understood. We employ nested sampling to fit mock data global signal and high- z galaxy ultraviolet luminosity function (UVLF) compare for first time emulated posteriors obtained using emulator globalemu “true” full model on which trained ARES . Of eight parameters we employ, four control star formation efficiency (SFE) thus can be constrained...
Abstract Accurate detection of the cosmological 21 cm global signal requires galactic foreground models that can remove power over 10 6 . Although and unavoidably exhibit overlap in their vector spaces inducing bias error extracted signal, a second source arises from inadequate models, i.e., cannot fit spectra down to noise level signal. We therefore test which seven commonly employed models—including nonlinear linear forward polynomials, maximally smooth polynomials—fit realistic simulated...
In 21-cm experimental cosmology, accurate characterization of a radio telescope's antenna beam response is essential to measure the signal. Computational electromagnetic (CEM) simulations estimate pattern and frequency by subjecting EM model different dependencies, or hyper-parameters, such as soil dielectric constant orientation with environment. However, it computationally expensive search all possible parameter spaces optimize design accurately represent level required for use systematic...
Abstract In 21 cm experimental cosmology, accurate characterization of a radio telescope’s antenna beam response is essential to measure the signal. Computational electromagnetic (CEM) simulations estimate pattern and frequency by subjecting EM model different dependencies, or hyperparameters, such as soil dielectric constant orientation with environment. However, it computationally expensive search all possible parameter spaces optimize design accurately represent level required for use...
Accurate detection of the cosmological 21-cm global signal requires galactic foreground models which can remove power over ~$10^6$. Although and unavoidably exhibit overlap in their vector-spaces inducing bias error extracted signal, a second source arises from inadequate models, i.e. cannot fit spectra down to noise level signal. We therefore test seven commonly employed -- including nonlinear linear forward-models, polynomials, maximally-smooth polynomials realistic simulated mock spectra,...
Although neural-network-based emulators enable efficient parameter estimation in 21-cm cosmology, the accuracy of such constraints is poorly understood. We employ nested sampling to fit mock data global signal and high-$z$ galaxy ultraviolet luminosity function (UVLF) compare for first time emulated posteriors obtained using emulator ${\tt globalemu}$ `true' full model on which trained ARES}$. Of eight parameters we employ, four control star formation efficiency (SFE), thus can be...