A5100707378- Radio Astronomy Observations and Technology
- Astrophysics and Cosmic Phenomena
- Galaxies: Formation, Evolution, Phenomena
- Particle physics theoretical and experimental studies
- Pulsars and Gravitational Waves Research
- High-Energy Particle Collisions Research
- Antenna Design and Optimization
- Quantum Chromodynamics and Particle Interactions
- Particle Detector Development and Performance
- Gamma-ray bursts and supernovae
- Radiation Detection and Scintillator Technologies
- Atomic and Subatomic Physics Research
- Neutrino Physics Research
- Astrophysical Phenomena and Observations
- Black Holes and Theoretical Physics
- Radio Wave Propagation Studies
- Geophysics and Gravity Measurements
- Astronomical Observations and Instrumentation
- Scientific Computing and Data Management
- Dark Matter and Cosmic Phenomena
- Computational Physics and Python Applications
- Rare-earth and actinide compounds
- Particle Accelerators and Free-Electron Lasers
- GNSS positioning and interference
- Plasma Diagnostics and Applications
Osaka University
2019-2024
Chinese Academy of Sciences
2015-2024
International Centre for Radio Astronomy Research
2012-2021
The University of Western Australia
2012-2021
Nanjing University
1993-2021
High Energy Accelerator Research Organization
2019-2020
RIKEN Center for Computational Science
2019-2020
Naval Research Laboratory Information Technology Division
2019-2020
Université Clermont Auvergne
2019-2020
Institute of High Energy Physics
2015-2020
The Murchison Widefield Array (MWA) has collected hundreds of hours Epoch Reionization (EoR) data and now faces the challenge overcoming foreground systematic contamination to reduce a cosmological measurement. We introduce several novel analysis techniques such as cable reflection calibration, hyper-resolution gridding kernels, diffuse model subtraction, quality control methods. Each change pipeline is tested against two dimensional power spectrum figure merit demonstrate improvement....
We describe a new low-frequency wideband radio survey of the southern sky. Observations covering 72-231MHz and Declinations south +30° have been performed with Murchison Widefield Array "extended" Phase I configuration over 2018-2020 will be processed to form data products including continuum polarisation images mosaics, multi-frequency catalogues, transient search data, ionospheric measurements. From pilot field described in this work, we publish an initial release 1,447 deg2 4 h≤ RA≤ 13 h,...
Detection of the cosmological neutral hydrogen signal from Epoch Reionization, and estimation its basic physical parameters, is principal scientific aim many current low-frequency radio telescopes. Here we describe Cosmological HI Power Spectrum Estimator (CHIPS), an algorithm developed implemented with data Murchison Widefield Array (MWA), to compute two-dimensional spherically-averaged power spectrum brightness temperature fluctuations. The motivations for CHIPS are application realistic...
Detection of 21~cm emission HI from the epoch reionization, at redshifts z>6, is limited primarily by foreground emission. We investigate signatures wide-field measurements and an all-sky model using delay spectrum technique that maps to object locations through signal delays between antenna pairs. demonstrate interferometric are inherently sensitive all scales, including largest angular owing nature measurements. These effects generic observations but shapes impact their amplitudes...
The upcoming next-generation large area radio continuum surveys can expect tens of millions sources, rendering the traditional method for morphology classification through visual inspection unfeasible. We present Claran — Classifying Radio sources Automatically with Neural networks a proof-of-concept source classifier based upon Faster Region-based Convolutional Neutral Networks method. Specifically, we train and test on FIRST WISE (Wide-field Infrared Survey Explorer) images from Galaxy Zoo...
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 We describe the motivation and design details of ‘Phase II’ upgrade Murchison Widefield Array radio telescope. The expansion doubles to 256 number antenna tiles deployed in array. new enhance capabilities several key science areas. Seventy-two are a regular configuration near existing array core. These surface brightness sensitivity will improve ability estimate slope Epoch Reionisation power spectrum by factor ∼3.5. remaining 56 on long baselines, doubling maximum baseline...
The Murchison Widefield Array (MWA), located in Western Australia, is one of the low-frequency precursors international Square Kilometre (SKA) project. In addition to pursuing its own ambitious science program, it also a testbed for wide range future SKA activities ranging from hardware, software data analysis. key programs MWA and require very high dynamic ranges, which challenges calibration imaging systems. Correct instrument accurate measurements source flux densities polarisations...
We present deep polarimetric observations at 154 MHz with the Murchison Widefield Array (MWA), covering 625 deg^2 centered on RA=0 h, Dec=-27 deg. The sensitivity available in our allows an in-band, frequency-dependent analysis of polarized structure for first time long wavelengths. Our suggests that structures are dominated by intrinsic emission but may also have a foreground Faraday screen component. At these wavelengths, compactness MWA baseline distribution provides excellent snapshot to...
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...
We present the results of a coordinated campaign conducted with Murchison Widefield Array (MWA) to shadow Fast Radio Bursts (FRBs) detected by Australian Square Kilometre Pathfinder (ASKAP) at 1.4 GHz, which resulted in simultaneous MWA observations seven ASKAP FRBs. de-dispersed $24$ $\times$ $1.28$ MHz images across $170-200$ band taken 0.5 second time resolution known dispersion measures (DMs) and arrival times bursts searched both within error regions (typically $\sim$ $10$ arcmin...
Detection of the epoch reionization H i signal requires a precise understanding intervening galaxies and AGN, both for instrumental calibration foreground removal. We present catalogue 7394 extragalactic sources at 182 MHz detected in RA = 0 field Murchison Widefield Array Epoch Reionization observation programme. Motivated by unprecedented requirements precision reliability we develop new methods source finding selection. apply machine learning to self-consistently classify relative 9490...
We present new radio continuum observations of NGC253 from the Murchison Widefield Array at frequencies between 76 and 227 MHz. model broadband spectral energy distribution for total flux density MHz 11 GHz. The spectrum is best described as a sum central starburst extended emission. component, corresponding to inner 500pc region galaxy, modelled an internally free-free absorbed synchrotron plasma, with turnover frequency around 230 emission component flattening low frequencies. find that...
We present a study of 16 HI-detected galaxies found in 178 hours observations from Epoch 1 the COSMOS HI Large Extragalactic Survey (CHILES). focus on two redshift ranges between 0.108 <= z 0.127 and 0.162 0.183 which are among worst affected by radio frequency interference (RFI). While this represents only 10% total coverage 18% expected time source compared to what will be full CHILES survey, we demonstrate that our data reduction pipeline recovers high quality even regions severely...
The Murchison Widefield Array (MWA) has observed the entire southern sky (Declination, $\delta <$ 30 deg) at low radio-frequencies, over range 72-231 MHz. These observations constitute GaLactic and Extragalactic All-sky MWA (GLEAM) Survey, we use extragalactic catalogue (Galactic latitude, $|b| >$ 10 to define GLEAM 4-Jy (G4Jy) Sample. This is a complete sample of 'brightest' radio-sources ($S_{\mathrm{151MHz}} 4 Jy), majority which are active galactic nuclei with powerful radio-jets....
We present the first low-frequency Murchison Widefield Array (MWA) radio continuum maps of Magellanic Clouds (MCs), using mosaics from GaLactic Extragalactic All-Sky MWA (GLEAM) survey. In this paper, we discuss overall morphology between 76 and 227 MHz compare them with neutral hydrogen maps, 1.4 GHz optical images. Variation diffuse emission is noticeable across Large Cloud (LMC) but absent bar Small (SMC). also measure integrated flux densities derive spectral indices for MCs. A double...
We compare first order (refractive) ionospheric effects seen by the Murchison Widefield Array (MWA) with ionosphere as inferred from Global Positioning System (GPS) data. The manifests itself a bulk position shift of observed sources across an MWA field view. These can be computed global maps provided GPS analysis centres, namely Center for Orbit Determination in Europe (CODE), using data globally distributed receivers. However, more accurate local estimates required precision radio...
We examine data from the Murchison Widefield Array (MWA) in frequency range 72 -- 102 MHz for a field-of-view that serendipitously contained interstellar object 'Oumuamua on 2017 November 28. Observations took place with time resolution of 0.5 s and 10 kHz. %This observation was undertaken another purpose but due to MWA's extremely large field-of-view, observed simultaneously. Based interesting highly unlikely suggestion is an spacecraft, some unusual orbital morphological characteristics,...
Abstract A new Goldstone particle named Majoron is introduced in order to explain the origin of neutrino mass via some physics models assuming that neutrinos are Majorana particles. By expanding signal region and using likelihood analysis, it becomes possible search for experiments originally designed conversion. For COMET experiment, sensitivity process able reach Phase-I Phase-II. Meanwhile, sensitivities future also discussed this article.
Abstract We provide the first in situ measurements of antenna element beam shapes Murchison Widefield Array. Most current processing pipelines use an assumed shape, which can cause absolute and relative flux density errors polarisation ‘leakage’. Understanding primary is then paramount importance, especially for sensitive experiments such as a measurement 21-cm line from epoch reionisation, where calibration requirements are so extreme that tile to variations may affect our ability make...
Abstract We apply two methods to estimate the 21-cm bispectrum from data taken within Epoch of Reionisation (EoR) project Murchison Widefield Array (MWA). Using acquired with Phase II compact array allows a direct be undertaken on multiple redundantly spaced triangles antenna tiles, as well an based gridded uv -plane. The and estimators are applied 21 h high-band (167–197 MHz; z = 6.2–7.5) 2016 2017 observing seasons. Analytic predictions for bias variance point-source foregrounds derived....
We present Murchison Widefield Array observations of the supernova remnant (SNR) 1987A between 72 and 230 MHz, representing lowest frequency source to date. This large lever arm in space constrains properties circumstellar medium created by progenitor SNR when it was its red supergiant phase. As late-2013, radio spectrum MHz 8.64 GHz does not show any deviation from a non-thermal power-law with spectral index $-0.74 \pm 0.02$. is consistent that derived at higher frequencies, beneath 100...