A5091165766- Radio Astronomy Observations and Technology
- Astrophysics and Cosmic Phenomena
- Astronomy and Astrophysical Research
- Radio Wave Propagation Studies
- Galaxies: Formation, Evolution, Phenomena
- Antenna Design and Optimization
- Soil Moisture and Remote Sensing
- Cosmology and Gravitation Theories
- Superconducting and THz Device Technology
- Geophysics and Gravity Measurements
- Astronomical Observations and Instrumentation
- Planetary Science and Exploration
- Scientific Research and Discoveries
- Particle accelerators and beam dynamics
- Particle Accelerators and Free-Electron Lasers
- Space Science and Extraterrestrial Life
- GNSS positioning and interference
- Real-time simulation and control systems
- Spectroscopy and Laser Applications
- Satellite Communication Systems
- Gamma-ray bursts and supernovae
- Electromagnetic Compatibility and Measurements
- Cardiovascular Function and Risk Factors
- Stellar, planetary, and galactic studies
- Astro and Planetary Science
University of California, Berkeley
2022-2025
Arizona State University
2015-2024
Universidad Católica de la Santísima Concepción
2018-2024
McGill University
2018-2021
Laboratory for Atmospheric and Space Physics
2016-2019
University of Colorado Boulder
2017-2018
University of Miami
2010-2013
We estimate the 21 cm Radio Background from accretion onto first intermediate-mass Black Holes between $z\approx 30$ and 16$. Combining potentially optimistic, but plausible, scenarios for black hole formation growth with empirical correlations luminosity radio-emission observed in low-redshift active galactic nuclei, we find that a model of holes forming molecular cooling halos is able to produce background exceeds Cosmic Microwave (CMB) at $z \approx 17$ though models involving larger halo...
ABSTRACT The observation of the global 21 cm signal produced by neutral hydrogen gas in intergalactic medium (IGM) during Dark Ages, Cosmic Dawn, and Epoch Reionization requires measurements with extremely well-calibrated wideband radiometers. We describe design characterization Mapper IGM Spin Temperature (MIST), which is a new ground-based, single-antenna, experiment. MIST was guided objectives avoiding systematics from an antenna ground plane cables around antenna, as well maximizing...
The Q/U Imaging ExperimenT (QUIET) employs coherent receivers at 43GHz and 95GHz, operating on the Chajnantor plateau in Atacama Desert Chile, to measure anisotropy polarization of CMB. QUIET primarily targets B modes from primordial gravitational waves. combination these frequencies gives sensitivity foreground contributions diffuse Galactic synchrotron radiation. Between 2008 October 2010 December, >10,000hours data were collected, first with 19-element array (3458hours) then 90-element...
Abstract We present new constraints on parameters of cosmic dawn and the epoch reionization derived from EDGES High-Band spectrum (90–190 MHz). The are probed by evaluating global 21 cm signals generated with recently developed Global21cm tool. This tool uses neural networks trained tested ∼30,000 spectra produced semi-numerical simulations that assume standard thermal evolution microwave background intergalactic medium. From our analysis, we constrain at 68% (1) minimum virial circular...
ABSTRACT The 21-cm signal of neutral hydrogen is a sensitive probe the Epoch Reionization (EoR), Cosmic Dawn, and Dark Ages. Currently, operating radio telescopes have ushered in data-driven era cosmology, providing first constraints on astrophysical properties sources that drive this signal. However, extracting information from data highly non-trivial requires rapid generation theoretical templates over wide range parameters. To end emulators are often employed, with previous efforts...
Abstract We summarize the second radio synchrotron background workshop, which took place on 2022 June 15–17 in Barolo, Italy. This meeting was convened because available measurements of diffuse zero level continue to suggest that it is several times higher than can be attributed known Galactic and extragalactic sources processes, rendering least well-understood electromagnetic at present a major outstanding question astrophysics. The workshop agreed next priorities for investigations this...
Comparing composite models for multi-component observational data is a prevalent scientific challenge. When fitting models, there exists the potential systematics from poor fit of one model component to be absorbed by another, resulting in providing an accurate aggregate but yielding biased posteriori estimates individual components. We begin defining classification scheme comparison scenarios, identifying two categories: category I, where with and predictive components are separable through...
The Q/U Imaging ExperimenT (QUIET) has observed the cosmic microwave background (CMB) at 43 and 95GHz. 43-GHz results have been published in QUIET Collaboration et al. (2011), here we report measurement of CMB polarization power spectra using 95-GHz data. This data set comprises 5337 hours observations recorded by an array 84 polarized coherent receivers with a total sensitivity 87 uK sqrt(s). Four low-foreground fields were observed, covering ~1000 square degrees effective angular...
We report absolutely calibrated measurements of diffuse radio emission between 90 and 190 MHz from the Experiment to Detect Global EoR Signature (EDGES). EDGES employs a wide beam zenith-pointing dipole antenna centred on declination -26.7$^\circ$. measure sky brightness temperature as function frequency averaged over 211 nights data acquired July 2015 March 2016. derive spectral index, $\beta$, local sidereal time (LST) find -2.60 > $\beta$ -2.62 $\pm$0.02 0 12 h LST. When Galactic Centre...
Abstract We report constraints on the global 21 cm signal due to neutral hydrogen at redshifts <?CDATA $14.8\geqslant z\geqslant 6.5$?> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mn>14.8</mml:mn> <mml:mo>≥</mml:mo> <mml:mi>z</mml:mi> <mml:mn>6.5</mml:mn> </mml:math> . derive our from low-foreground observations of average sky brightness spectrum conducted with EDGES High-band instrument between 2015 September 7 and October 26. Observations were...
The Q/U Imaging ExperimenT (QUIET) is designed to measure polarization in the Cosmic Microwave Background, targeting imprint of inflationary gravitational waves at large angular scales (~ 1 degree). Between 2008 October and 2010 December, two independent receiver arrays were deployed sequentially on a 1.4 m side-fed Dragonian telescope. polarimeters which form focal planes use highly compact design based High Electron Mobility Transistors (HEMTs) that provides simultaneous measurements...
Abstract The redshifted 21 cm monopole is expected to be a powerful probe of the epoch first stars and galaxies ( <?CDATA $10\lt z\lt 35$?> ). global signal sensitive thermal ionization state hydrogen gas thus provides tracer sources energetic photons—primarily hot accreting black holes—which ionize heat high redshift intergalactic medium (IGM). This paper presents strategy for observations spectrum with realizable instrument placed in low-altitude lunar orbit, performing night-time 40–120...
Abstract We use the sky-average spectrum measured by EDGES High-band (90–190 MHz) to constrain parameters of early galaxies independent absorption feature at 78 MHz reported Bowman et al. These represent traditional models cosmic dawn and epoch reionization produced with 21cmFAST simulation code. The considered are (1) UV ionizing efficiency ( ζ ); (2) minimum halo virial temperature hosting efficient star-forming <?CDATA ${T}_{\mathrm{vir}}^{\min }$?> (3) integrated soft-band X-ray...
Abstract The Mapper of the IGM Spin Temperature (MIST) is a new ground-based, single-antenna, radio experiment attempting to detect global 21 cm signal from Dark Ages and Cosmic Dawn. A significant challenge in this measurement frequency dependence, or chromaticity, antenna beam directivity. MIST observes with above soil without metal ground plane, directivity sensitive electrical characteristics soil. In paper, we use simulated observations study how detection Dawn affected by We simulate...
Foreground subtraction in global redshifted 21 cm measurements is limited by frequency-dependent (chromatic) structure antenna beam patterns. Chromatic beams couple angular structures Galactic foreground emission to spectral that may not be removed smooth functional forms. We report results for simulations based on two dipole antennas used the Experiment Detect Global EoR Signature (EDGES). The residual levels simulated foreground-subtracted spectra are found differ substantially between...
The EDGES High-Band experiment aims to detect the sky-average brightness temperature of $21$-cm signal from Epoch Reionization (EoR) in redshift range $14.8 \gtrsim z 6.5$. To probe this redshifted signal, conducts single-antenna measurements frequency $90-190$ MHz Murchison Radio-astronomy Observatory Western Australia. In paper, we describe current strategy for calibration receiver and report results instrument used $2015-2016$ observational campaign. We propagate uncertainties antenna...
We report the spectral index of diffuse radio emission between 50 and 100 MHz from data collected with two implementations Experiment to Detect Global EoR Signature (EDGES) low-band system. EDGES employs a wide beam zenith-pointing dipole antenna centred on declination $-26.7^\circ$. measure sky brightness temperature as function frequency averaged over 244 nights acquired 14 September 2016 27 August 2017. derive index, $\beta$, local sidereal time (LST) using night-time two-parameter...
ABSTRACT Accurately accounting for spectral structure in spectrometer data induced by instrumental chromaticity on scales relevant detection of the 21-cm signal is among most significant challenges global analysis. In publicly available Experiment to Detect Global Epoch Reionization Signature low-band set, this complicating suppressed using beam-factor-based correction (BFCC), which works dividing a sky-map-weighted model instrument beam. Several analyses these have employed models that...
Abstract The response of the antenna is a source uncertainty in measurements with Experiment to Detect Global Epoch Reionization Signature (EDGES). We aim validate electromagnetic beam model low-band (50–100 MHz) dipole comparisons between models and against data. find that simulations simplified over an infinite perfectly conducting ground plane are, one exception, robust changes numerical solver code or algorithm. For actual finite realistic soil properties, we two out three solvers agree...
The observation of the global 21 cm signal produced by neutral hydrogen gas in intergalactic medium (IGM) during Dark Ages, Cosmic Dawn, and Epoch Reionization requires measurements with extremely well-calibrated wideband radiometers. We describe design characterization Mapper IGM Spin Temperature (MIST), which is a new ground-based, single-antenna, experiment. MIST was guided objectives avoiding systematics from an antenna ground plane cables around antenna, as well maximizing instrument's...
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...