Adam Lanman
A5036958287- Radio Astronomy Observations and Technology
- Astrophysics and Cosmic Phenomena
- Pulsars and Gravitational Waves Research
- Radio Wave Propagation Studies
- Gamma-ray bursts and supernovae
- Antenna Design and Optimization
- GNSS positioning and interference
- Electromagnetic Compatibility and Measurements
- Galaxies: Formation, Evolution, Phenomena
- Millimeter-Wave Propagation and Modeling
- Superconducting and THz Device Technology
- Microwave Engineering and Waveguides
- Soil Moisture and Remote Sensing
- Particle Accelerators and Free-Electron Lasers
- Astronomy and Astrophysical Research
- Astronomical Observations and Instrumentation
- Statistical and numerical algorithms
- earthquake and tectonic studies
- Gyrotron and Vacuum Electronics Research
- Cosmology and Gravitation Theories
- Pulsed Power Technology Applications
- Optical measurement and interference techniques
- Adaptive optics and wavefront sensing
- Seismic and Structural Analysis of Tall Buildings
- Advanced Wireless Communication Techniques
Brown University
2018-2025
Massachusetts Institute of Technology
2024-2025
McGill University
2022-2024
Kavli Institute for Particle Astrophysics and Cosmology
2024
Providence College
2024
Rhodes University
2023
John Brown University
2019-2021
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...
We present the discovery of 25 new repeating fast radio burst (FRB) sources found among CHIME/FRB events detected between 2019 September 30 and 2021 May 1. The were using a clustering algorithm that looks for multiple co-located on sky having similar dispersion measures (DMs). repeaters have DMs ranging from $\sim$220 pc cm$^{-3}$ to $\sim$1700 cm$^{-3}$, include exhibited as few two bursts many twelve. report statistically significant difference in both DM extragalactic (eDM) distributions...
Abstract We present the host galaxies of four apparently nonrepeating fast radio bursts (FRBs), FRB 20181223C, 20190418A, 20191220A, and 20190425A, reported in first Canadian Hydrogen Intensity Mapping Experiment (CHIME/FRB) catalog. Our selection these FRBs is based on a planned hypothesis testing framework where we search all CHIME/FRB Catalog-1 events that have low extragalactic dispersion measure (<100 pc cm −3 ), with high Galactic latitude (∣ b ∣ > 10°) saved baseband data....
Abstract We report the discovery of repeating fast radio burst (FRB) source FRB 20240209A using Canadian Hydrogen Intensity Mapping Experiment (CHIME)/FRB telescope. detected 22 bursts from this repeater between 2024 February and July, 6 which were also recorded at Outrigger station k’niʔatn k’l ⌣ stk’masqt (KKO). The multiple very long baseline interferometry localizations 66 km CHIME–KKO baseline, each with a different vector orientation due to repeater’s high decl. ∼86°, enabled combined...
Abstract The discovery and localization of FRB 20240209A by the Canadian Hydrogen Intensity Mapping Fast Radio Burst (CHIME/FRB) experiment marks first repeating localized with CHIME/FRB Outriggers adds to small sample FRBs associated host galaxies. Here we present Keck Gemini observations that reveal a redshift z = 0.1384 ± 0.0004. We perform stellar population modeling jointly fit optical through mid-IR data infer median mass log( M * / ⊙ ) 11.35 0.01 mass-weighted age ~11 Gyr,...
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...
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 The repeating FRB 20201124A was first discovered by CHIME/FRB in November of 2020, after which it seen to repeat a few times over several months. It entered period high activity April 2021, at time observatories recorded tens hundreds more bursts from the source. These follow-up observations enabled precise localization and host-galaxy identification. In this paper, we report on CHIME/FRB-detected 20201124A, including their best-fit morphologies, fluences, arrival times. large...
Abstract The CHIME/FRB project has detected hundreds of fast radio bursts (FRBs), providing an unparalleled population to statistically probe the foreground media that they illuminate. One such medium is ionized halo Milky Way (MW). We estimate total Galactic electron column density from FRB dispersion measures (DMs) as a function latitude using four different estimators, including ones assume spherical symmetry MW and imply more latitudinal variation in density. Our observation-based...
Abstract In 2021, a catalog of 536 fast radio bursts (FRBs) detected with the Canadian Hydrogen Intensity Mapping Experiment (CHIME) telescope was released by CHIME/FRB Collaboration. This large collection bursts, observed single instrument and uniform selection effects, has advanced our understanding FRB population. Here we update results for 140 these FRBs which channelized raw voltage (“baseband”) data are available. With voltages measured telescope’s antennas, it is possible to maximize...
Abstract Localizing fast radio bursts (FRBs) to their host galaxies is an essential step better understanding origins and using them as cosmic probes. The Canadian Hydrogen Intensity Mapping Experiment (CHIME)/FRB Outriggers program aims add very long baseline interferometry localization capabilities CHIME, such that FRBs may be localized tens of milliarcsecond precision at the time discovery, more than sufficient for galaxy identification. first-built outrigger telescope Outrigger (KKO),...
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 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...
Fast radio bursts (FRBs) represent an exciting frontier in the study of gravitational lensing, due to their brightness, extragalactic nature, and compact, coherent characteristics emission. In a companion work [Z. Kader C. Leung, Phys. Rev. D 106, 043016 (2022).], we use novel interferometric method search for gravitationally lensed FRBs time domain using detected by CHIME/FRB. There, dechannelize autocorrelate electric field data at resolution 1.25 ns. This enables whose emission is...
Abstract Interferometric arrays seeking to measure the 21 cm signal from epoch of reionization (EOR) must contend with overwhelmingly bright emission foreground sources. Accurate recovery will require precise calibration array, and several new avenues for have been pursued in recent years, including methods using redundancy antenna configuration. The newly upgraded Phase II Murchison Widefield Array (MWA) is first interferometer that has large numbers redundant baselines while retaining good...
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...