M. J. Lynch
A5068276767- Radio Astronomy Observations and Technology
- Astrophysics and Cosmic Phenomena
- Galaxies: Formation, Evolution, Phenomena
- Radio Wave Propagation Studies
- Marine and coastal ecosystems
- Antenna Design and Optimization
- Atmospheric and Environmental Gas Dynamics
- Atmospheric aerosols and clouds
- Cryospheric studies and observations
- Remote Sensing in Agriculture
- Gamma-ray bursts and supernovae
- GNSS positioning and interference
- Solar and Space Plasma Dynamics
- Oceanographic and Atmospheric Processes
- Meteorological Phenomena and Simulations
- Climate change and permafrost
- Arctic and Antarctic ice dynamics
- Landslides and related hazards
- Calibration and Measurement Techniques
- Astronomical Observations and Instrumentation
- Ocean Waves and Remote Sensing
- Fire effects on ecosystems
- History and Developments in Astronomy
- Urban Heat Island Mitigation
- Ionosphere and magnetosphere dynamics
Curtin University
2014-2024
International Centre for Radio Astronomy Research
2011-2018
Canadian Institute for Theoretical Astrophysics
2016
University of Toronto
2016
The Murchison Widefield Array (MWA) is one of three Square Kilometre Precursor telescopes and located at the Radio-astronomy Observatory in Shire mid-west Western Australia, a location chosen for its extremely low levels radio frequency interference. MWA operates frequencies, 80-300 MHz, with processed bandwidth 30.72 MHz both linear polarisations, consists 128 aperture arrays (known as tiles) distributed over ~3 km diameter area. Novel hybrid hardware/software correlation real-time imaging...
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...
We are developing the Precision Array for Probing Epoch of Re-ionization (PAPER) to detect 21 cm emission from early universe, when first stars and galaxies were forming. describe overall experiment strategy architecture summarize two PAPER deployments: a four-antenna array in low radio frequency interference (RFI) environment Western Australia an eight-antenna at prototyping site NRAO facilities near Green Bank, WV. From these activities we report on system performance, including primary...
The Murchison Widefield Array (MWA) is a dipole-based aperture array synthesis telescope designed to operate in the 80-300 MHz frequency range. It capable of wide range science investigations, but initially focused on three key projects. These are detection and characterization 3-dimensional brightness temperature fluctuations 21cm line neutral hydrogen during Epoch Reionization (EoR) at redshifts from 6 10, solar imaging remote sensing inner heliosphere via propagation effects signals...
Abstract Significant new opportunities for astrophysics and cosmology have been identified at low radio frequencies. The Murchison Widefield Array is the first telescope in southern hemisphere designed specifically to explore low-frequency astronomical sky between 80 300 MHz with arcminute angular resolution high survey efficiency. will enable advances along four key science themes, including searching redshifted 21-cm emission from EoR early Universe; Galactic extragalactic all-sky surveys;...
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,...
In this paper we explore for the first time relative magnitudes of three fundamental sources uncertainty, namely, foreground contamination, thermal noise and sample variance in detecting HI power spectrum from Epoch Reionization (EoR). We derive limits on sensitivity a Fourier synthesis telescope to detect EoR based its array configuration statistical representation images made by instrument. use Murchison Widefield Array (MWA) our studies. Using unified framework estimating signal...
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...
We present first results from radio observations with the Murchison Widefield Array seeking to constrain power spectrum of 21 cm brightness temperature fluctuations between redshifts 11.6 and 17.9 (113 75 MHz). 3 h were conducted over two nights significantly different levels ionospheric activity. use these data assess impact systematic errors at low frequency, including ionosphere radio-frequency interference, on a measurement. find that after 1–3 integration presented here, our...
We present a Stokes I, Q and U survey at 189 MHz with the Murchison Widefield Array 32 element prototype covering 2400 deg2. The has 15.6 arcmin angular resolution achieves noise level of 15 mJy beam−1. demonstrate novel interferometric data analysis that involves calibration drift scan data, integration through co-addition warped snapshot images, deconvolution point-spread function forward modeling. point source catalog down to flux limit 4 Jy. detect polarization from only one sources, PMN...
ABSTRACT We introduce the Fast Holographic Deconvolution method for analyzing interferometric radio data. Our new is an extension of A-projection/software-holography/forward modeling analysis techniques and shares their precision deconvolution wide-field polarimetry, while being significantly faster than current implementations that use full direction-dependent antenna gains. Using data from MWA 32 prototype, we demonstrate effectiveness our algorithm. may be particularly important upcoming...
We present the 21 cm power spectrum analysis approach of Murchison Widefield Array Epoch Reionization project. In this paper, we compare outputs multiple pipelines for purpose validating statistical limits cosmological hydrogen at redshifts between 6 and 12. Multiple, independent, data calibration reduction are used to make on a fiducial night data. Comparing imaging stages highlights differences in calibration, foreground subtraction calculation. The spectra found using these different...
Abstract We present the results of an approximately 6 100 deg 2 104–196 MHz radio sky survey performed with Murchison Widefield Array during instrument commissioning between 2012 September and December: MWACS. The data were taken as meridian drift scans two different 32-antenna sub-arrays that available period. covers 20.5 h < RA 8.5 h, − 58° Dec −14°over three frequency bands centred on 119, 150 180 MHz, image resolutions 6–3 arcmin. catalogue has 3 arcmin angular resolution a typical...
Using the final 128 antenna locations of Murchison Widefield Array (MWA), we calculate its sensitivity to Epoch Reionization (EoR) power spectrum red- shifted 21 cm emission for a fiducial model and provide tools any model. Our calculation takes into account synthesis rotation, chro- matic asymmetrical baseline effects, excludes modes that will be contaminated by foreground subtraction. For model, MWA capable 14{\sigma} detection EoR signal with one full season observation on two fields (900...
We present a search for transient and variable radio sources at 154 MHz with the Murchison Widefield Array 32-tile prototype. 51 images were obtained that cover field of view 1430 deg2 centred on Hydra A. The observations over three days in 2010 March 2011 April May. mean cadence was 26 min there additional temporal information day year time-scales. explore variability sample 105 low-frequency within field. Four bright (S > 6 Jy) candidate identified displayed low levels short time-scale (26...
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...
In this paper we present observations, simulations, and analysis demonstrating the direct connection between location of foreground emission on sky its in cosmological power spectra from interferometric redshifted 21 cm experiments. We begin with a heuristic formalism for understanding mapping coordinates into cylindrically averaged measurements used by experiments, focus effects instrument beam response associated sidelobes. then demonstrate analyzing both simulated observed data Murchison...
Type III solar radio bursts are the Sun's most intense and frequent nonthermal emissions. They involve two critical problems in astrophysics, plasma physics, space physics: how collective processes produce radiation magnetic reconnection occurs changes energy into kinetic energy. Here events identified definitively Solar Dynamics Observatory UV-EUV data, with strong upward downward pairs of jets, current sheets, cusp-like geometries on top time-varying loops, outflows along open field lines....
We present the first spectroscopic images of solar radio transients from prototype for Murchison Widefield Array (MWA), observed on 2010 March 27. Our observations span instantaneous frequency band 170.9-201.6 MHz. Though our observing period is characterized as a `low' to `medium' activity, one broadband emission feature and numerous short-lived, narrowband, non-thermal features are evident. data represent significant advance in low imaging, enabling us follow spatial, spectral, temporal...
Using the new wideband capabilities of Australia Telescope Compact Array (ATCA), we obtain spectra for PKS 1718-649, a well-known gigahertz-peaked spectrum radio source. The observations, between approximately 1 and 10 GHz over three epochs spanning 21 months, reveal variability both above spectral peak at ~3 below peak. combination low high frequency cannot be easily explained using single absorption mechanism, such as free-free or synchrotron self-absorption. We find that 1718-649 its are...
We present the results of a survey for low frequency radio emission from 17 known exoplanetary systems with Murchison Widefield Array. This sample includes 13 that have not previously been targeted observations. detected no at 154 MHz, and put 3 sigma upper limits in range 15.2-112.5 mJy on this emission. also searched circularly polarised made detections, obtaining 3.4-49.9 mJy. These are comparable best existing literature translate to luminosity between 1.2 x 10^14 W 1.4 10^17 if is...
The Murchison Widefield Array (MWA) is a new low frequency interferomeric radio telescope. MWA the precursor to Square Kilometre (SKA) and first of three SKA precursors be operational, supporting varied science mission ranging from attempted detection Epoch Reionisation monitoring solar flares space weather. We explore possibility that can used for purposes Space Situational Awareness (SSA). In particular we propose as an element passive radar facility operating in range 87.5 - 108 MHz (the...
Abstract The Murchison Widefield Array is a Square Kilometre Precursor. telescope located at the Radio–astronomy Observatory in Western Australia. MWA consists of 4 096 dipoles arranged into 128 dual polarisation aperture arrays forming connected element interferometer that cross-correlates signals from all 256 inputs. A hybrid approach to correlation task employed, with some processing stages being performed by bespoke hardware, based on Field Programmable Gate Arrays, and others Graphics...