M. E. Bell
A5033506961- Radio Astronomy Observations and Technology
- Astrophysics and Cosmic Phenomena
- Galaxies: Formation, Evolution, Phenomena
- Gamma-ray bursts and supernovae
- Pulsars and Gravitational Waves Research
- Astronomical Observations and Instrumentation
- Astronomy and Astrophysical Research
- Astrophysical Phenomena and Observations
- Radio Wave Propagation Studies
- GNSS positioning and interference
- Geophysics and Gravity Measurements
- Stellar, planetary, and galactic studies
- Astrophysics and Star Formation Studies
- Particle Accelerators and Free-Electron Lasers
- Solar and Space Plasma Dynamics
- Astro and Planetary Science
- Geophysics and Sensor Technology
- Superconducting and THz Device Technology
- Ionosphere and magnetosphere dynamics
- Antenna Design and Optimization
- Adaptive optics and wavefront sensing
- Particle accelerators and beam dynamics
- Planetary Science and Exploration
- Dark Matter and Cosmic Phenomena
- Statistical and numerical algorithms
University of Technology Sydney
2018-2024
Petroleum Geo-Services (United Kingdom)
2024
University of Newcastle Australia
2023
Astronomy and Space
2014-2022
Commonwealth Scientific and Industrial Research Organisation
2014-2022
ARC Centre of Excellence for All-sky Astrophysics
2013-2018
The University of Sydney
2012-2018
Australia Telescope National Facility
2014-2017
University of Hertfordshire
2017
University of Southampton
2010-2015
LOFAR, the LOw-Frequency ARray, is a new-generation radio interferometer constructed in north of Netherlands and across europe. Utilizing novel phased-array design, LOFAR covers largely unexplored low-frequency range from 10-240 MHz provides number unique observing capabilities. Spreading out core located near village Exloo northeast Netherlands, total 40 stations are nearing completion. A further five have been deployed throughout Germany, one station has built each France, Sweden, UK....
Astronomical wide-field imaging of interferometric radio data is computationally expensive, especially for the large volumes created by modern non-coplanar many-element arrays. We present a new imager that uses w-stacking algorithm and can make use w-snapshot algorithm. The performance dependences casa's w-projection our are analysed analytical functions derived describe required computing cost both imagers. On from Murchison Widefield Array, we find method to be an order magnitude faster...
Abstract Using the Murchison Widefield Array (MWA), low-frequency Square Kilometre precursor located in Western Australia, we have completed GaLactic and Extragalactic All-sky MWA (GLEAM) survey, present resulting extragalactic catalogue, utilizing first year of observations. The catalogue covers 24 831 square degrees, over declinations south +30° Galactic latitudes outside 10° plane, excluding some areas such as Magellanic Clouds. It contains 307 455 radio sources with 20 separate flux...
Low frequency radio waves, while challenging to observe, are a rich source of information about pulsars. The LOw Frequency ARray (LOFAR) is new interferometer operating in the lowest 4 octaves ionospheric "radio window": 10-240MHz, that will greatly facilitate observing pulsars at low frequencies. Through huge collecting area, long baselines, and flexible digital hardware, it expected LOFAR revolutionize astronomy frequencies visible from Earth. next-generation telescope pathfinder Square...
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,...
The Murchison Widefield Array (MWA) is a new low-frequency interferometric radio telescope built in Western Australia at one of the locations future Square Kilometre (SKA). We describe automated radio-frequency interference (RFI) detection strategy implemented for MWA, which based on AOFlagger platform, and present 72-231-MHz RFI statistics from 10 observing nights. removes 1.1% data. digital TV (DTV) observed 3% time due to occasional ionospheric or atmospheric propagation. After excision,...
Faraday rotation measurements using the current and next generation of low-frequency radio telescopes will provide a powerful probe astronomical magnetic fields. However, achieving full potential these requires accurate removal time-variable ionospheric contribution. We present ionFR, code that calculates amount for specific epoch, geographic location, line-of-sight. ionFR uses number publicly available, GPS-derived total electron content maps most recent release International Geomagnetic...
Pulsars emit low-frequency radio waves through to high-energy gamma-rays that are generated anywhere from the surface out edges of magnetosphere. Detecting correlated mode changes in multi-wavelength emission is therefore key understanding physical relationship between these sites. Through simultaneous observations, we have detected synchronous switching and X-ray properties PSR B0943+10. When pulsar a sustained 'bright' mode, X-rays show only an un-pulsed, non-thermal component. Conversely,...
The aim of the LOFAR Epoch Reionization (EoR) project is to detect spectral fluctuations redshifted HI 21cm signal. This signal weaker by several orders magnitude than astrophysical foreground signals and hence, in order achieve this, very long integrations, accurate calibration for stations ionosphere reliable removal are essential. One prospective observing windows EoR will be centered at North Celestial Pole (NCP). We present results from observations NCP window using highband antenna...
Abstract The Australian Square Kilometre Array Pathfinder (ASKAP) will give us an unprecedented opportunity to investigate the transient sky at radio wavelengths. In this paper we present VAST, ASKAP survey for Variables and Slow Transients. VAST exploit wide-field capabilities of enable discovery investigation variable phenomena from local cosmological, including flare stars, intermittent pulsars, X-ray binaries, magnetars, extreme scattering events, interstellar scintillation, supernovae,...
We report the detection of an ultra-bright fast radio burst (FRB) from a modest, 3.4-day pilot survey with Australian Square Kilometre Array Pathfinder. The was conducted in wide-field fly's-eye configuration using phased-array-feed technology deployed on array to instantaneously observe effective area $160$ deg$^2$, and achieve exposure totaling $13200$ deg$^2$ hr. constrain position FRB 170107 region $8'\times8'$ size (90% containment) its fluence be $58\pm6$ Jy ms. spectrum shows sharp...
We present the Multifrequency Snapshot Sky Survey (MSSS), first northern-sky LOFAR imaging survey. In this introductory paper, we describe in detail motivation and design of Compared to previous radio surveys, MSSS is exceptional due its intrinsic multifrequency nature providing information about spectral properties detected sources over more than two octaves (from 30 160 MHz). The broadband frequency coverage, together with fast survey speed generated by LOFAR's multibeaming capabilities,...
Abstract We present the data and initial results from first pilot survey of Evolutionary Map Universe (EMU), observed at 944 MHz with Australian Square Kilometre Array Pathfinder (ASKAP) telescope. The covers $270 \,\mathrm{deg}^2$ an area covered by Dark Energy Survey, reaching a depth 25–30 $\mu\mathrm{Jy\ beam}^{-1}$ rms spatial resolution $\sim$ 11–18 arcsec, resulting in catalogue 220 000 sources, which 180 are single-component sources. Here we together (where available) optical...
We report the detection of 48 millisecond pulsars (MSPs) out 75 observed thus far using LOFAR in frequency range 110-188 MHz. have also detected three MSPs nine 38-77 This is largest sample ever at these low frequencies, and half were for first time frequencies below 200 present average pulse profiles MSPs, their effective widths, flux densities compare with higher observing frequencies. The flux-calibrated, multifrequency are publicly available via EPN Database Pulsar Profiles. values...
M87 is a giant elliptical galaxy located in the centre of Virgo cluster, which harbours supermassive black hole mass 6.4x10^9 M_sun, whose activity responsible for extended (80 kpc) radio lobes that surround galaxy. The energy generated by matter falling onto central ejected and transferred to intra-cluster medium via relativistic jet morphologically complex systems buoyant bubbles, rise towards edges halo. Here we present first observations made with new Low-Frequency Array (LOFAR) at...
The low frequency array (LOFAR), is the first radio telescope designed with capability to measure emission from cosmic-ray induced air showers in parallel interferometric observations. In $\sim 2\,\mathrm{years}$ of observing, 405 events energy range $10^{16} - 10^{18}\,\mathrm{eV}$ have been detected band $30 80\,\mathrm{MHz}$. Each these registered up $\sim1000$ independent antennas resulting measurements unprecedented detail. This article describes dataset, as well analysis pipeline, and...
The characteristic outer scale of turbulence and the ratio random to ordered components magnetic field are key parameters characterise in interstellar gas, which affects propagation cosmic rays within Galaxy. We provide new constraints those two parameters. use LOw Frequency ARray (LOFAR) image diffuse continuum emission Fan region at (l,b) (137.0,+7.0) 80"x70" resolution range [146,174] MHz. detect multi-scale fluctuations Galactic synchrotron compute their power spectrum. Applying...
Dispersion in the interstellar medium is a well known phenomenon that follows simple relationship, which has been used to predict time delay of dispersed radio pulses since late 1960s. We performed wide-band simultaneous observations four pulsars with LOFAR (at 40-190 MHz), 76-m Lovell Telescope 1400 MHz) and Effelsberg 100-m 8000 test accuracy dispersion law over broad frequency range. In this paper we present results these show accurate better than 1 part 100000 across our observing band....
In the lead-up to Square Kilometre Array (SKA) project, several next-generation radio telescopes and upgrades are already being built around world. These include APERTIF (The Netherlands), ASKAP (Australia), eMERLIN (UK), VLA (USA), e-EVN (based in Europe), LOFAR Meerkat (South Africa), Murchison Widefield (MWA). Each of these new instruments has different strengths, coordination surveys between them can help maximise science from each them. A continuum survey is planned on with primary...
We present first results from a LOFAR census of non-recycled pulsars. The includes almost all such pulsars known (194 sources) at declinations ${\rm Dec}> 8^\circ$ and Galactic latitudes $|{\rm Gb}| > 3^\circ$, regardless their expected flux densities scattering times. Each pulsar was observed for $\geq 20$ minutes in the contiguous frequency range 110--188 MHz. Full-Stokes data were recorded. dispersion measures, densities, calibrated total intensity profiles 158 detected sample. median...
We present the highest-quality polarisation profiles to date of 16 non-recycled pulsars and four millisecond pulsars, observed below 200 MHz with LOFAR high-band antennas. Based on profiles, we perform an initial investigation expected observational effects resulting from propagation polarised emission in pulsar magnetosphere interstellar medium. The predictions magnetospheric birefringence have been tested using spectra pulse width fractional multifrequency data. derived offer only partial...
We have conducted two pilot surveys for radio pulsars and fast transients with the Low-Frequency Array (LOFAR) around 140 MHz here report on first low-frequency fast-radio burst limit discovery of new pulsars. The survey, LOFAR Pilot Pulsar Survey (LPPS), observed a large fraction northern sky, ~1.4 x 10^4 sq. deg, 1-hr dwell times. Each observation covered ~75 deg using 7 independent fields formed by incoherently summing high-band antenna fields. second Tied-Array (LOTAS), spanned ~600...