A5040167680- Galaxies: Formation, Evolution, Phenomena
- Radio Astronomy Observations and Technology
- Astrophysics and Cosmic Phenomena
- Astronomy and Astrophysical Research
- Gamma-ray bursts and supernovae
- Astrophysical Phenomena and Observations
- Astronomical Observations and Instrumentation
- Stellar, planetary, and galactic studies
- Adaptive optics and wavefront sensing
- Pulsars and Gravitational Waves Research
- Superconducting and THz Device Technology
- Radio Wave Propagation Studies
- Astrophysics and Star Formation Studies
- Superconducting Materials and Applications
- Scientific Measurement and Uncertainty Evaluation
- Spectroscopy and Laser Applications
- Soil Moisture and Remote Sensing
- Particle Accelerators and Free-Electron Lasers
- CCD and CMOS Imaging Sensors
- Healthcare professionals’ stress and burnout
- Seismic Imaging and Inversion Techniques
- Optimism, Hope, and Well-being
- Plant and Fungal Species Descriptions
- Electromagnetic Compatibility and Noise Suppression
- Health and Well-being Studies
Durham University
2024
South African Radio Astronomy Observatory
2019-2024
Rhodes University
2019-2024
University of Scranton
2024
ARC Centre of Excellence for All-sky Astrophysics
2022
The University of Sydney
2022
International Centre for Radio Astronomy Research
2016-2021
Curtin University
2016-2021
University of Pretoria
2021
MKS Instruments (United States)
2021
In this paper we describe the first data release of Visible and Infrared Survey Telescope for Astronomy (VISTA) Deep Extragalactic Observations (VIDEO) survey. VIDEO is a ~12degree^2 survey in near-infrared Z,Y,J,H K_s bands, specifically designed to enable evolution galaxies large structures be traced as function both epoch environment from present day out z=4, active galactic nuclei (AGN) most massive up into reionization. With its depth area, will able fully explore period Universe where...
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...
We describe Hubble Space Telescope (HST) imaging of 10 the 20 ESO Distant Cluster Survey (EDisCS) fields. Each ~40 square arcminute field was imaged in F814W filter with Advanced Camera for Surveys Wide Field Camera. Based on these data, we present visual morphological classifications ~920 sources per that are brighter than I_auto=23 mag. use to quantify content intermediate-redshift (0.5 < z 0.8) galaxy clusters within HST survey region. The EDisCS results, combined previously published...
We present MeerKAT 1.28 GHz total-intensity, polarization, and spectral-index images covering the giant (projected length $l \approx 1.57$~Mpc) X-shaped radio source PKS~2014$-$55 with an unprecedented combination of brightness sensitivity angular resolution. They show clear "double boomerang" morphology hydrodynamical backflows from straight main jets deflected by large oblique hot-gas halo host galaxy PGC~064440. The magnetic field orientation in follows flow lines through secondary wings....
Abstract We present the full panchromatic afterglow light-curve data of GW170817, including new radio as well archival optical and X-ray data, between 0.5 940 days post-merger. By compiling all reprocessing a subset it, we have evaluated impact differences in processing or flux determination methods used by different groups attempted to mitigate these provide more uniform set. Simple power-law fits light curve indicate t 0.86±0.04 rise, −1.92±0.12 decline, peak occurring at 155 ± 4 days. The...
Understanding the interplay between black-hole accretion and star formation, how to disentangle two, is crucial our understanding of galaxy formation evolution. To investigate, we use a combination optical near-infrared photometry select sample 74 quasars from VISTA Deep Extragalactic Observations (VIDEO) survey, over 1 deg2. The depth VIDEO allows us study very low rates and/or lower-mass black holes, 26 per cent candidate quasar has been spectroscopically confirmed. We radio-stacking...
In order to understand the role of radio-quiet quasars (RQQs) in galaxy evolution, we must determine relative levels accretion and star-formation activity within these objects. Previous work at low radio flux densities has shown that makes a significant contribution total emission, contrast with other quasar studies suggest star formation dominates. To investigate, use 70 RQQs from Spitzer–Herschel Active Galaxy Survey. These are all z ∼ 1, thereby minimizing evolutionary effects, have been...
We present MeerKAT 1000 MHz and 1400 observations of a bright radio galaxy in the southern hemisphere, ESO~137-006. The lies at centre massive merging Norma cluster. continuum images (rms ~0.02 mJy/beam ~10" resolution) reveal new features that have never been seen before: collimated synchrotron threads yet unknown origin, which link extended bent lobes most prominent these stretches projection for about 80 kpc is 1 width. spectrum steep, with spectral index up to $\alpha\simeq 2$ between MHz.
Radio wavelengths offer the unique possibility of tracing total star-formation rate in galaxies, both obscured and unobscured.As such, they may provide most robust measurement history Universe.In this chapter we highlight constraints that SKA can place on evolution Universe, survey area required to overcome sample variance, spatial resolution requirements, along with multi-wavelength ancillary data will play a major role maximising scientific promise SKA.The combination depth means trace...
We present a multi-wavelength study of the gaseous medium surrounding nearby active galactic nucleus (AGN), Fornax A. Using MeerKAT, ALMA, and MUSE observations, we reveal complex distribution atomic (H I ), molecular (CO), ionised gas in its centre along radio jets. By studying multi-scale kinematics multi-phase gas, presence concurrent AGN feeding feedback phenomena. Several clouds an extended 3 kpc filament – perpendicular to jets inner disk ( r ≲ 4.5 kpc) show highly-turbulent...
The nearby elliptical galaxy IC4296 has produced a large (510 kpc) low-luminosity radio source with typical FR I core/jet/lobe morphology. unprecedented combination of brightness sensitivity, dynamic range, and angular resolution new 1.28 GHz MeerKAT continuum image reveals striking morphological features which we call threads, ribbons, rings. threads are faint narrow emission originating where helical Kelvin-Helmholtz instabilities disrupt the main jets. ribbons smooth regions between jets...
The GaLactic and Extragalactic All-sky MWA survey (GLEAM) is a radio continuum at 72-231 MHz of the whole sky south declination +30 deg, carried out with Murchison Widefield Array (MWA). In this paper, we derive source counts from GLEAM data 200, 154, 118 88 MHz, to flux density limit 50, 80, 120 290 mJy respectively, correcting for ionospheric smearing, incompleteness blending. These are more accurate than other in literature similar frequencies as result large area covered survey's...
We report the discovery of two new giant radio galaxies (GRGs) using MeerKAT International GHz Tiered Extragalactic Exploration (MIGHTEE) survey. Both GRGs were found within a 1 deg^2 region inside COSMOS field. They have redshifts z=0.1656 and z=0.3363 physical sizes 2.4Mpc 2.0Mpc, respectively. Only cores these clearly visible in previous high resolution VLA observations, since diffuse emission lobes was resolved out. However, excellent sensitivity uv coverage telescope allowed this to be...
We present an analysis of a new 120 deg$^{2}$ radio continuum image the Large Magellanic Cloud (LMC) at 888 MHz with bandwidth 288 and beam size $13\rlap{.}^{\prime\prime}9\times12\rlap{.}^{\prime\prime}1$, from Australian Square Kilometre Array Pathfinder (ASKAP) processed as part Evolutionary Map Universe (EMU) survey. The median Root Mean Squared noise is 58 $\mu$Jy beam$^{-1}$. catalogue 54,612 sources, divided over GOLD list (30,866 sources) complete down to 0.5 mJy uniformly across...
Abstract The remnant phase of a radio galaxy begins when the jets launched from an active galactic nucleus are switched off. To study fraction galaxies in phase, we take advantage $8.31$ deg $^2$ subregion GAMA 23 field which comprises surveys covering frequency range 0.1–9 GHz. We present sample 104 compiled observations conducted by Murchison Widefield Array (216 MHz), Australia Square Kilometer Pathfinder (887 and Telescope Compact (5.5 GHz). adopt ‘absent core’ criterion to identify 10...
We have used the Karl G. Jansky Very Large Array to image ~100 sq. deg. of SDSS Stripe 82 at 1-2 GHz. The survey consists 1,026 snapshot observations 2.5 minutes duration, using hybrid CnB configuration. has good sensitivity diffuse, low surface brightness structures and extended radio emission, making it highly synergistic with existing 1.4 GHz region. principal data products are continuum images, 16 x 10 arcsecond resolution, a catalogue containing 11,782 point Gaussian components...
Abstract In this work, we apply self-supervised learning with instance differentiation to learn a robust, multipurpose representation for image analysis of resolved extragalactic continuum images. We train multi-use model which compresses our unlabelled data into structured, low dimensional can be used variety downstream tasks (e.g. classification, similarity search). exceed baseline supervised Fanaroff–Riley classification performance by statistically significant margin, reducing the test...
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 ($S_{\mathrm{151MHz}} 4 Jy), majority which are active galactic nuclei with powerful radio-jets....
Abstract The low-frequency polarisation properties of radio sources are poorly studied, particularly in statistical samples. However, the new generation telescopes, such as Murchison Widefield Array (the precursor for component Square Kilometre Array) offers an opportunity to probe physics at very low frequencies. In this paper, we present a catalogue linearly polarised detected 216 MHz, using data from Galactic and Extragalactic All-sky survey. Our covers Declination range –17° –37° 24 h...
The recent detection of the quasi-stellar object (QSO) VIKING J231818.3$-$311346 (hereafter VIK J2318$-$3113) at redshift $z=6.44$ in Rapid ASKAP Continuum Survey (RACS) uncovered its radio-loud nature, making it one most distant known to date this class. By using data from several radio surveys Galaxy and Mass Assembly 23$^\mathrm{h}$ field dedicated follow-up, we were able constrain spectrum J2318$-$3113 observed range $\sim$0.1--10 GHz. At high frequencies (0.888--5.5 GHz frame) QSO...
ABSTRACT Spectral variability of radio sources encodes information about the conditions intervening media, source structure, and emission processes. With new low-frequency interferometers observing over wide fractional bandwidths, studies spectral for a large population extragalactic are now possible. Using two epochs observations from GaLactic Extragalactic All-sky Murchison Widefield Array (GLEAM) survey that were taken one year apart, we search across 100–230 MHz 21 558 sources. We...
Abstract We present a detailed analysis of the radio galaxy PKS $2250{-}351$ , giant 1.2 Mpc projected size, its host galaxy, and environment. use data from Murchison Widefield Array, upgraded Giant Metre-wavelength Radio Telescope, Australian Square Kilometre Array Pathfinder, Australia Telescope Compact to model jet power age. Optical IR come Galaxy And Mass Assembly (GAMA) survey provide information on GAMA spectroscopy confirms that lies at $z=0.2115$ in irregular, likely unrelaxed,...
We have undertaken a systematic study of FRI and FRII radio galaxies with the upgraded Giant Metrewave Radio Telescope (uGMRT) MeerKAT. The main goal is to explore whether unprecedented few $\mu$Jy sensitivity reached in range 550-1712 MHz at resolution $\sim4^{\prime\prime}-7^{\prime\prime}$ reveals new features emission which might need us revise our current classification scheme for classical galaxies. In this paper we present results first set four galaxies, i.e. 4C 12.02, 12.03, CGCG...