A5006174724- Radio Astronomy Observations and Technology
- Astrophysics and Cosmic Phenomena
- Galaxies: Formation, Evolution, Phenomena
- Astrophysics and Star Formation Studies
- Stellar, planetary, and galactic studies
- Solar and Space Plasma Dynamics
- Astronomical Observations and Instrumentation
- Scientific Research and Discoveries
- Gamma-ray bursts and supernovae
- Pulsars and Gravitational Waves Research
- Astrophysical Phenomena and Observations
- Geomagnetism and Paleomagnetism Studies
- Ionosphere and magnetosphere dynamics
- Geophysics and Gravity Measurements
- Astronomy and Astrophysical Research
- Astro and Planetary Science
- GNSS positioning and interference
- Statistical and numerical algorithms
- Urban Heat Island Mitigation
- Neutrino Physics Research
- Plant Water Relations and Carbon Dynamics
- Magnetic and Electromagnetic Effects
- Scientific Measurement and Uncertainty Evaluation
- Remote Sensing in Agriculture
- Particle physics theoretical and experimental studies
Australian National University
2021-2025
University of Alberta
2024
Canadian Institute for Theoretical Astrophysics
2024
University of Toronto
2024
Max Planck Institute for Radio Astronomy
2017-2023
Max Planck Society
2017
University of Hong Kong
2016
McGill University
2004
Aims. This work provides an update to existing reconstructions of the Galactic Faraday rotation sky by processing almost all data sets available at end year 2020. Observations extra-Galactic sources in recent years have further illuminated previously underconstrained southern celestial sky, as well parts inner disc Milky Way, along with other regions. has culminated all-sky set 55 190 points, thereby comprising a significant expansion on 41 330 used previous works. At same time, this novelty...
Abstract The structure and dynamics of the star-forming disk Small Magellanic Cloud (SMC) have long confounded us. SMC is widely used as a prototype for galactic physics at low metallicity, yet we fundamentally lack an understanding its interstellar medium (ISM). In this work, present new model by comparing kinematics young, massive stars with ISM traced high-resolution observations neutral atomic hydrogen (H i ) from Galactic Australian Square Kilometre Array Pathfinder survey....
Galactic plane radio surveys play a key role in improving our understanding of wide range astrophysical phenomena. Performing such survey using the latest interferometric telescopes produces large data rates necessitating shift towards fully or quasi-real-time analysis with being stored for only time required to process them. We present here overview and setup 3000 hour Max-Planck-Institut fuer Radioastronomie (MPIfR) MeerKAT Plane (MMGPS). The is unique by operating commensal mode,...
We present the most sensitive and detailed view of neutral hydrogen (HI) emission associated with Small Magellanic Cloud (SMC), through combination data from Australian Square Kilometre Array Pathfinder (ASKAP) Parkes (Murriyang), as part Galactic (GASKAP) pilot survey. These GASKAP-HI observations, for first time, reveal HI in SMC on similar physical scales other important tracers interstellar medium, such molecular gas dust. The resultant image cube possesses an rms noise level 1.1 K (1.6...
Faraday rotation measures (RMs) have been used for many studies of cosmic magnetism, and in most cases having more RMs is beneficial those studies. This has lead to development RM surveys that produced large catalogs, as well meta-catalogs collecting from different publications. However, it difficult take full advantage all these the individual catalogs published places, formats. In addition, polarization spectra determine are rarely published, limiting ability re-analyze data new methods or...
We use the Milky Way neutral hydrogen (HI) absorption and emission spectra from Galactic Australian Square Kilometre Array Pathfinder (GASKAP) Phase II Pilot survey along with toy models to investigate effects of stacking multicomponent on measurements peak optical depth spin temperature. Shifting by in emission, 'primary' components shifted 0 km s$^{-1}$ are correctly averaged. Additional individual sightlines averaged non-centred velocities, producing a broader shallower 'secondary'...
Abstract We report the observations of radio shell supernova remnant (SNR) G310.6–1.6 at 943 MHz from Evolutionary Map Universe (EMU) and Polarization Sky Survey Universe’s Magnetism (POSSUM) surveys by using Australian Square Kilometre Array Pathfinder (ASKAP). detect polarized emission central pulsar wind nebula (PWN) with rotation measures varying –696 rad m −2 to –601 . measure integrated flux density be 36.4 ± 2.2 mJy derive a spectral index α pwn = −0.4 0.1 for PWN −0.7 0.3 SNR shell....
Turbulence plays a crucial role in shaping the structure of interstellar medium. The ratio three-dimensional density contrast ($\sigma_{\rho/\rho_0}$) to turbulent sonic Mach number ($\mathcal{M}$) an isothermal, compressible gas describes solenoidal compressive modes acceleration field gas, and is parameterised by turbulence driving parameter: $b=\sigma_{\rho/\rho_0}/\mathcal{M}$. parameter ranges from $b=1/3$ (purely solenoidal) $b=1$ compressive), with $b=0.38$ characterising natural...
ABSTRACT We present the largest Galactic neutral hydrogen H i absorption survey to date, utilizing Australian SKA Pathfinder Telescope at an unprecedented spatial resolution of 30 arcsec. This survey, GASKAP-H i, unbiasedly targets 2714 continuum background sources over 250 square degrees in direction Magellanic Clouds, a significant increase compared total 373 observed by previous surveys across entire Milky Way. aim investigate physical properties cold (CNM) and warm (WNM) atomic gas Way...
Abstract Magnetic fields in the ionized medium of disk and halo Milky Way impose Faraday rotation on linearly polarized radio emission. We compare two surveys mapping Galactic rotation, one showing measures extragalactic sources seen through Galaxy, depth diffuse synchrotron emission from Global Magneto-Ionic Medium Survey. Comparing data sets 5° × 10° bins shows good agreement at intermediate latitudes, < ∣ b 50°, little correlation between them lower higher latitudes. Where they agree,...
Abstract The Australian SKA Pathfinder (ASKAP) radio telescope has carried out a survey of the entire Southern Sky at 887.5 MHz. wide area, high angular resolution, and broad bandwidth provided by low-band Rapid ASKAP Continuum Survey (RACS-low) allow production next-generation rotation measure (RM) grid across Sky. Here we introduce this project as Spectral Polarisation in Cutouts Extragalactic sources from RACS (SPICE-RACS). In our first data release, image 30 RACS-low fields Stokes I , Q...
Pulsar wind nebulae (PWNe) are suggested to be acceleration sites of cosmic rays in the Galaxy. While magnetic field plays an important role process, previous observations configurations PWNe rare, particularly for evolved systems. We present a radio polarization study "Snail" PWN inside supernova remnant G327.1-1.1 using Australia Telescope Compact Array. This is believed have been recently crushed by (SN) reverse shock. The morphology composed main circular body with finger-like...
Observing the magnetic fields of low-mass interacting galaxies tells us how they have evolved over cosmic time and their importance in galaxy evolution. We measured Faraday rotation 80 extra-galactic radio sources behind Small Magellanic Cloud (SMC) using CSIRO Australia Telescope Compact Array (ATCA) with a frequency range 1.4 -- 3.0 GHz. Both sensitivity our observations source density are an order magnitude improvement on previous measurements this galaxy. The SMC generally produces...
The NRAO VLA Sky Survey (NVSS) Rotation Measure (RM) catalogue is invaluable for the study of cosmic magnetism. However, RM values reported in it can be affected by n$\pi$-ambiguity, resulting deviations from true multiples +-652.9 rad m-2. We therefore set off to observationally constrain fraction sources this ambiguity. New broadband spectro-polarimetric observations were performed with Karl G. Jansky Very Large Array (VLA) at 1--2 GHz, 23 n$\pi$-ambiguity candidates selected their...
ABSTRACT Faraday rotation measure (RM) is arguably the most practical observational tracer of magnetic fields in diffuse circumgalactic medium (CGM). We sample synthetic skies Milky Way-like galaxies TNG50 IllustrisTNG project by placing an observer inside at a solar circle-like position. Our RM grids emulate specifications current and upcoming surveys; NRAO VLA Sky Survey (NVSS), Polarisation Universe’s Magnetism (POSSUM), future Square Kilometre Array (SKA1-mid) polarization survey. It has...
The Milky Way is one of the very few spiral galaxies known to host large-scale magnetic field reversals. existence reversal in first Galactic quadrant near Sagittarius arm has been well established, yet poorly characterised due insufficient number reliable Faraday depths (FDs) from extragalactic radio sources (EGSs) through this region. We have therefore performed broadband (1-2 GHz) spectro-polarimetric observations with Karl G. Jansky Very Large Array (VLA) determine FD values 194 EGSs...
The S -band Polarisation All Sky Survey (SPASS/ATCA) rotation measure (RM) catalogue is the largest broadband RM to date, increasing density in sparse southern sky. Through analysis of this catalogue, we report a latitude dependency Faraday complexity polarised sources within 10° Galactic plane towards inner Galaxy. In study, aim investigate trend with follow-up observations using Australia Telescope Compact Array (ATCA). We observe 95 from SPASS/ATCA at 1.1–3.1 GHz ATCA’s 6 km...
Context . Fast radio bursts (FRBs) are poised to become important cosmological tools in the near future, as number of observed FRBs is increasing rapidly with multiple surveys underway. A large sample will soon have available dispersion measures (DMs) and rotation (RMs), which can be used study cosmic baryon density intergalactic magnetic field. However, DM RM consists contributions that must quantified estimate medium (IGM). Aims In this paper, we one such contribution RM, namely, FRB host...
Abstract We present initial results from the Polarisation Sky Survey of Universe’s Magnetism (POSSUM), analyzing 22,817 Faraday Rotation Measures (RMs) with median uncertainties 1.2 rad m−2 across 1,520 square degrees to study magnetised gas associated 55 nearby galaxy groups (z ≲ 0.025) halo masses between 1012.5 and 1014.0 M⊙. identify two distinct phases: Intragroup Medium (IGrM) within 0–2 splashback radii Warm-Hot Intergalactic (WHIM) extending 2 7 radii. These phases enhance standard...
The NRAO VLA Sky Survey (NVSS) Rotation Measure (RM) catalogue has enabled numerous studies in cosmic magnetism, and will continue being a unique dataset complementing future polarisation surveys. Robust comparisons with these new surveys however require further understandings the systematic effects present NVSS RM catalogue. In this paper, we make careful between our on-axis broadband observations Karl G. Jansky Very Large Array results for 23 sources. We found that two unpolarised sources...
ABSTRACT High-spatial-resolution H i observations have led to the realization that nearby (within few hundreds of parsecs) Galactic atomic filamentary structures are aligned with ambient magnetic field. Enabled by high-quality data from Australian Square Kilometre Array Pathfinder (ASKAP) radio telescope for ASKAP survey, we investigate potential alignment $\gtrsim\!{10}\, {\rm pc}$-scale filaments in Small Magellanic Cloud (SMC). Using Rolling Hough Transform technique automatically...
ABSTRACT Neutral hydrogen (H i) bubbles and shells are common in the interstellar medium (ISM). Studying their properties provides insight into characteristics of local ISM as well galaxy which reside. We report detection magnetic fields associated with superbubbles nearby irregular galaxy, Small Magellanic Cloud (SMC). Using Polarisation Sky Survey Universe’s Magnetism (POSSUM) pilot survey, we obtain a high-density grid ($\approx 25 \, \rm sources\, deg^{-2}$) Faraday rotation measure (RM)...
ABSTRACT Studying the Magellanic System can help us understand role that magnetic fields play in evolution and structure of interacting low-mass galaxies. We have measured Faraday rotation measure (RM) 185 extra-galactic radio sources behind Large Cloud (LMC) to determine field LMC. These observations were conducted with CSIRO Australia Telescope Compact Array (ATCA) a frequency range 1.6–3.0 GHz. Our double density grid RMs for With these new RM conjunction previous measurements, we find...