A5087705345- Radio Astronomy Observations and Technology
- Astrophysics and Cosmic Phenomena
- Galaxies: Formation, Evolution, Phenomena
- Gamma-ray bursts and supernovae
- Astronomy and Astrophysical Research
- Astronomical Observations and Instrumentation
- Atmospheric Ozone and Climate
- Calibration and Measurement Techniques
- Stellar, planetary, and galactic studies
- Solar and Space Plasma Dynamics
- Astrophysical Phenomena and Observations
- Geophysics and Gravity Measurements
- Space exploration and regulation
- Dark Matter and Cosmic Phenomena
- Animal Diversity and Health Studies
- Particle accelerators and beam dynamics
- Planetary Science and Exploration
- Astrophysics and Star Formation Studies
- Mathematics Education and Pedagogy
- Gyrotron and Vacuum Electronics Research
- Computational Physics and Python Applications
- Radiation Detection and Scintillator Technologies
- Rangeland Management and Livestock Ecology
- Ionosphere and magnetosphere dynamics
- Superconducting Materials and Applications
International Centre for Radio Astronomy Research
2017-2023
Commonwealth Scientific and Industrial Research Organisation
2010-2023
Astronomy and Space
2011-2023
Curtin University
2017-2023
ARC Centre of Excellence for All-sky Astrophysics
2017-2018
Australia Telescope National Facility
2010-2015
UNSW Sydney
2010-2015
North Bengal University
1991
We present the full source catalogue from Australia Telescope 20 GHz (AT20G) Survey. The AT20G is a blind radio survey carried out at with Compact Array (ATCA) 2004 to 2008, and covers whole sky south of declination 0°. presented here an order magnitude larger than any previous high-frequency sources, includes 5890 sources above flux-density limit 40 mJy. All have total intensity polarization measured GHz, most −15° also near-simultaneous measurements 5 8 GHz. A 1559 were detected in...
The Australia Telescope 20 GHz (AT20G) survey is a blind of the whole Southern sky at with follow-up observations 4.8, 8.6, and carried out Compact Array (ATCA). In this paper we present an analysis radio spectral properties in total intensity polarisation, sizes, optical identifications, redshifts sample 5808 extragalactic sources catalogue confirmed over excluding strip Galactic latitude |b|<1.5deg. has flux density limit 40 mJy. Completeness been measured as function scan region density....
We report the first astrophysical application of technique wide-field interplanetary scintillation (IPS) with Murchison Widefield Array (MWA). This powerful allows us to identify and measure sub-arcsecond compact components in low-frequency radio sources across large areas sky without need for long-baseline interferometry or ionospheric calibration. present results a 5-min observation 30 × deg2 MWA field at 162 MHz 0.5 s time resolution. Of 2550 continuum detected this field, 302 (12 per...
We present the first dedicated observations of Interplanetary Scintillation (IPS) with Murchison Widefield Array. have developed a synthesis imaging technique, tailored to properties modern 'large-N' low-frequency radio telescopes. This allows us image variability on IPS time-scales across 900 deg2 simultaneously. show that for our observations, sampling rate just 2 Hz is sufficient resolve signature most sources. develop tests ensure separated from ionospheric or instrumental variability....
Our current understanding of radio-loud AGN comes predominantly from studies at frequencies 5 GHz and below. With the recent completion Australia Telescope 20 (AT20G) survey, we can now gain insight into high-frequency radio properties AGN. This paper presents supplementary information on AT20G sources in form optical counterparts redshifts. Optical were identified using SuperCOSMOS database redshifts found either 6dF Galaxy survey or literature. We also report 144 new For outside Galactic...
We present the high-angular-resolution catalogue for Australia Telescope 20 GHz (AT20G) survey, using 6-km antenna data at baselines of ∼4500 m Compact Array. have used to produce visibility that separates compact active galactic nuclei (AGNs) from extended radio sources 0.15 arcsec angular scale, corresponding linear size scale 1 kpc redshifts higher than 0.7. find population be dominated by AGNs constituting 77 per cent total in AT20G. introduce visibility-spectra diagnostic plot, produced...
We present polarisation data for 180 extragalactic sources extracted from the Australia Telescope 20 GHz (AT20G) survey catalog, and observed with Compact Array during a dedicated, high sensitivity run. For sake of completeness we information 7 extended 9-yr WMAP coadded maps at 23 GHz. The full sample 187 constitutes 99% complete brighter than S(20 GHz)=500mJy selection epoch declination <-30 deg. has 91.4% detection rate in 20GHz (94% if considering sub-sample point like sources). have...
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 ($S_{\mathrm{151MHz}} 4 Jy), majority which are active galactic nuclei with powerful radio-jets....
We use high angular resolution data, measured from visibility of sources at the longest baseline 4500 m Australia Telescope Compact Array (ATCA), for 20 GHz (AT20G) survey to obtain size information > 94% AT20G sources. confirm previous result that due frequency GHz, source population is strongly dominated by compact (79%). At 0.15 arcseconds limit, we show a very strong correlation between and extended with flat steep-spectrum respectively. Thus, provide firm physical basis traditional...
We present a source catalogue and first results from deep, blind radio survey carried out at 20 GHz with the Australia Telescope Compact Array, follow-up observations 5.5, 9 18 GHz. The (AT20G) deep pilot covers total area of 5 deg2 in Chandra Deep Field South Stripe 82 Sloan Digital Sky Survey. estimate to be 90 per cent complete above 2.5 mJy. Of 85 sources detected, 55 have steep spectra (|$\alpha _{1.4}^{20} < -0.5$|) 45 flat or inverted \ge -0.5$|). steep-spectrum tend single...
We have shown previously that the Murchison Widefield Array (MWA), can detect hundreds of Interplanetary Scintillation (IPS) sources simultaneously across a field view $\sim30^\circ$ in extent. To test if we use this capability to track heliospheric structures, undertook search 88 hours MWA IPS data, and identified an observation likely significant Coronal Mass Ejection (CME) view. demonstrate single 5-minute are able localise image CME $\sim$33 after launch at elongation $\sim37^\circ$ from...
ABSTRACT We report an ASKAP search for associated H i 21-cm absorption against bright radio sources from the Molonglo Reference Catalogue (MRC) 1-Jy sample. The uses pilot survey data First Large Absorption Survey in (FLASH) covering redshift range 0.42 &lt; z 1.00. From a sample of 62 MRC galaxies and quasars, we three new detections absorption, yielding overall detection fraction $1.8\,{{\,\rm per\,cent}}^{+4.0\,{{\,\rm per\,cent}}}_{-1.5\,{{\,\rm per\,cent}}}$. detected systems...
We cross-matched the six-year Swift/Burst Alert Telescope (BAT) survey of Active Galactic Nuclei (AGN) with AT20G radio southern sky, which is one largest high-frequency surveys available.With these data we investigated possible correlation between and X-ray emission at highest frequencies.We found 37 AGN a high probability association (> 80%), among 19 are local Seyfert galaxies (with median redshift z = 0.03) 18 blazars.We that ≈ 20% detected in hard X-rays also bright sources 20 GHz, but...
We use Murchison Widefield Array (MWA) observations of interplanetary scintillation (IPS) to determine the source counts point (<0.3 arcsec extent) sources and all with some subarcsecond structure, at 162 MHz. have developed methodology derive these directly from IPS observables, while taking into account changes in sensitivity across survey area. The compact structure follow behaviour dominant population above ∼3 Jy but below this they show Euclidean behaviour. compare our those predicted...
We report on a search for low-frequency radio variability in 944 bright (>4 Jy at 154 MHz) unresolved, extragalactic sources monitored monthly several years with the Murchison Widefield Array. In majority of sources, we find very low levels typical modulation indices <5 per cent. detect 15 candidate variables that show significant long-term (>2.8 yr) time-averaged |$\overline{M}=3.1\!-\! 7.1$| With 7/15 these variable having peaked spectral energy distributions, and only 5.7 cent overall...
Cold massive cores are one of the earliest manifestations high-mass star formation. Following detection SiO emission from G333.125−0.562, a cold core, further investigations physics, chemistry and dynamics this object has been carried out. Mopra NANTEN2 molecular line profile observations, Australia Telescope Compact Array (ATCA) continuum maps Spitzer 24 70 μm images were obtained. These new data constrain properties prime example very early stages A model for source was constructed...
Around 10 per cent of bright low-frequency radio sources observed with the Murchison Wide-field Array (MWA) show strong interplanetary scintillation (IPS) on time-scales a few seconds, implying that almost all their emission comes from compact component less than 0.5 arcsec in angular size. Most these objects are steep-spectrum or MHz-peaked spectrum sources. We have used mid-infrared data Infrared Survey Explorer (WISE) catalogue to search for host galaxies 65 strongly scintillating MWA and...
We provide radio spectral properties at high frequencies (1≤ν (GHz) ≤ 20) for 65 planetary nebulae in the Australia Telescope 20 GHz (AT20G) survey, identified from our list of sources that show flat-spectrum (α > −0.5) and are well resolved 0.15 arcsec angular size scale. this method very effectively identifies thermal like (and H ii regions). In analysis spectra a subset 37 nebulae, we find no clear evidence either excess flux optically thin region proposed literature, or non-thermal...
Abstract We describe the parameters of a low-frequency all-sky survey compact radio sources using Interplanetary Scintillation, undertaken with Murchison Widefield Array. While this gives important complementary information to low-resolution survey, providing on sub-arsecond structure every source, kind has not been attempted in era imaging arrays such as Array and LOw Frequency Here we set out capabilities describing limitations imposed by heliocentric observing geometry instrument itself....
Abstract The entire southern sky (Declination, $\delta< 30^{\circ}$ ) has been observed using the Murchison Widefield Array (MWA), which provides radio imaging of $\sim$ 2 arcmin resolution at low frequencies (72–231 MHz). This is GaLactic and Extragalactic All-sky MWA (GLEAM) Survey, we have previously used a combination visual inspection, cross-checks against literature, internal matching to identify ‘brightest’ radio-sources ( $S_{\mathrm{151\,MHz}}>4$ Jy) in extragalactic catalogue...
The GaLactic and Extragalactic All-sky Murchison Widefield Array (GLEAM) is a radio continuum survey at 76-227 MHz of the entire southern sky (Declination $<+30\deg$) with an angular resolution $\approx 2$ arcmin. In this paper, we combine GLEAM data optical spectroscopy from 6dF Galaxy Survey to construct sample 1,590 local (median $z \approx 0.064$) sources $S_{200\,\mathrm{MHz}} > 55$ mJy across area 16,700~\mathrm{deg}^{2}$. From spectra, identify dominant physical process responsible...
ABSTRACT Past studies of compact active galactic nuclei (AGNs), the dominant population at high radio frequencies, selected them using flat spectral index criteria. This biases sample due to steepening AGN spectra frequencies. We improve upon this by selecting 3610 AGNs their angular size information ($\lesssim$0.15 arcsec scale) from Australia Telescope 20 GHz (AT20G) high-angular resolution catalogue. cross-match these against Wide-field Infrared Survey Explorer AllWISE catalogue and...
This study examined the effectiveness of online interactive modules in improving mathematical proficiency among Grade VI students Phuentsholing Primary School, focusing on concepts ordering fractions and rotation. The mixed-methods approach was used where 27 participated three-week intervention involving learning tools. Data were collected through pre-tests post-tests, surveys, observations. results analyzed using Statistical Package for Social Sciences (SPSS version 22) it demonstrated...