J. Hickish
A5028442017- Gamma-ray bursts and supernovae
- Radio Astronomy Observations and Technology
- Astrophysics and Cosmic Phenomena
- Antenna Design and Optimization
- Radio Wave Propagation Studies
- SAS software applications and methods
- Space Science and Extraterrestrial Life
- Astronomy and Astrophysical Research
- Galaxies: Formation, Evolution, Phenomena
- Electromagnetic Compatibility and Measurements
- Pulsars and Gravitational Waves Research
- Astronomical Observations and Instrumentation
- Microwave Engineering and Waveguides
- Planetary Science and Exploration
- Astrophysical Phenomena and Observations
- Particle Accelerators and Free-Electron Lasers
- Soil Moisture and Remote Sensing
- Superconducting and THz Device Technology
- Millimeter-Wave Propagation and Modeling
- Stellar, planetary, and galactic studies
- Scientific Research and Discoveries
- Particle Detector Development and Performance
- Gyrotron and Vacuum Electronics Research
- Advanced Wireless Communication Techniques
- Optical measurement and interference techniques
University of California, Berkeley
2016-2025
University of Washington
2024
Brown University
2021-2023
University of Cambridge
2015-2018
University of Oxford
2010-2016
Search for Extraterrestrial Intelligence
2016
University of Malta
2015
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 present results of the coordinated observing campaign that made first subarcsecond localization a Fast Radio Burst, FRB 121102. During this campaign, we simultaneous detection an burst by multiple telescopes: VLA at 3 GHz and Arecibo Observatory 1.4 GHz. Of nine bursts detected Very Large Array GHz, four had coverage other observatories. use multi-observatory constraints modeling seen only to confirm earlier showing spectra are not well modeled power law. find characterized ~500 MHz...
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...
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...
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 report on the MIT Epoch of Reionization (MITEoR) experiment, a pathfinder low-frequency radio interferometer whose goal is to test technologies that improve calibration precision and reduce cost high-sensitivity 3D mapping required for 21 cm cosmology. MITEoR accomplishes this by using massive baseline redundancy, which enables both automated correlator reduction. demonstrate quantify power robustness redundancy scalability precision. find parameters precisely describe effect instrument...
The Arcminute Microkelvin Imager (AMI) telescopes located at the Mullard Radio Astronomy Observatory near Cambridge have been significantly enhanced by implementation of a new digital correlator with 1.2 MHz spectral resolution. This system has replaced 750-MHz resolution analogue lag-based correlator, and was designed to mitigate effects radio frequency interference, particularly from geostationary satellites that contaminate observations low declinations. upgraded instrument consists 18...
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...
We report on a search for engineered signals from sample of 692 nearby stars using the Robert C. Byrd Green Bank Telescope, undertaken as part $Breakthrough~Listen~Initiative$ extraterrestrial intelligence. Observations were made over 1.1$-$1.9 GHz (L band), with three sets five-minute observations primary targets, interspersed secondary targets. By comparing "ON" and "OFF" we are able to identify terrestrial interference place limits presence putative civilizations inhabiting environs...
We present the target selection for Breakthrough Listen search extraterrestrial intelligence during first year of observations at Green Bank Telescope, Parkes Telescope and Automated Planet Finder. On way to observing 1,000,000 nearby stars in technological signals, we three main sets objects plan observe addition a smaller sample exotica. choose 60 nearest stars, all within 5.1 pc from sun. Such offer potential faint radio signals transmitters having power similar those on Earth. add list...
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...
After more than 26 years in quiescence, the black hole transient V404 Cyg went into a luminous outburst June 2015, and additional activity was detected late December of same year. Here, we present an optical spectroscopic follow-up mini-outburst, together with X-ray, radio monitoring that spanned month. Strong flares gradually increasing intensity are three spectral ranges during ~10 days following Swift trigger. Our spectra reveal presence fast outflowing wind, as implied by detection P-Cyg...
Low-frequency radio continuum observations of edge-on galaxies are ideal to study cosmic-ray electrons (CREs) in halos via synchrotron emission and measure magnetic field strengths. We obtained new the spiral galaxy NGC 891 at 129-163 MHz with LOw Frequency ARray (LOFAR) 13-18 GHz Arcminute Microkelvin Imager (AMI) combine them recent high-resolution Very Large Array (VLA) 1-2 GHz, enabling us over two orders magnitude frequency. The spectrum integrated nonthermal flux density can be fitted...
Here, we report on the detection and verification of Fast Radio Burst FRB 180301, which occurred UTC 2018 March 1 during Breakthrough Listen observations with Parkes telescope. Full-polarization voltage data were captured--a first for non-repeating FRBs--allowing coherent de-dispersion additional tests. The coherently de-dispersed dynamic spectrum 180301 shows complex, polarized frequency structure over a small fractional bandwidth. As was detected close to geosynchronous satellite band time...
We report on late time radio and X-ray observations of the tidal disruption event candidate ASASSN-14li, covering first 1000 days decay phase. For $\sim200$ emission fade in concert. This phase is better fit by an exponential at wavelengths, while well described either or canonical $t^{-5/3}$ assumed for events. The correlation between during this period can be as $L_{R}\propto L_{X}^{1.9\pm0.2}$. After 400 $15.5\,\textrm{GHz}$ has reached a plateau level $244\pm8\,\mu\textrm{Jy}$ which it...
We describe in general terms the practical use astronomy of a higher-order statistical quantity called Spectral Kurtosis (SK), and first implementation SK-enabled firmware F-engine (Fourier transform-engine) digital FX correlator for Expanded Owens Valley Solar Array (EOVSA). The development theory SK is summarized, leading to an expression generalized that applicable both spectrometers those not specifically designed SK. also give means computing estimator thresholds its application as...