A5040045152- Radio Astronomy Observations and Technology
- Astrophysics and Cosmic Phenomena
- Astrophysics and Star Formation Studies
- Stellar, planetary, and galactic studies
- Solar and Space Plasma Dynamics
- Astronomical Observations and Instrumentation
- Astronomy and Astrophysical Research
- Geophysics and Gravity Measurements
- Superconducting and THz Device Technology
- Geomagnetism and Paleomagnetism Studies
- Galaxies: Formation, Evolution, Phenomena
- Scientific Research and Discoveries
- Advanced Frequency and Time Standards
- Magnetic and Electromagnetic Effects
- Pulsars and Gravitational Waves Research
- Calibration and Measurement Techniques
- Gamma-ray bursts and supernovae
- Flow Measurement and Analysis
- Soil Moisture and Remote Sensing
- Irrigation Practices and Water Management
- Ionosphere and magnetosphere dynamics
- Earthquake Detection and Analysis
- Geophysical and Geoelectrical Methods
- Adaptive optics and wavefront sensing
- Atomic and Molecular Physics
University of Alberta
2007-2023
Herzberg Institute of Astrophysics
2004-2021
National Research Council Canada
2007-2021
Dominion Astrophysical Observatory
2010-2016
SKA Telescope, South Africa
2012-2016
University of Calgary
2014-2015
Max Planck Institute for Radio Astronomy
2002-2010
Covington and Burling
2008-2010
Max Planck Society
2006
Australia Telescope National Facility
2005
Abstract The future of centimetre and metre-wave astronomy lies with the Square Kilometre Array (SKA), a telescope under development by consortium 17 countries that will be 50 times more sensitive than any existing radio facility. Most key science for SKA addressed through large-area imaging Universe at frequencies from few hundred MHz to GHz. Australian Pathfinder (ASKAP) is technology demonstrator aimed in mid-frequency range, achieves instantaneous wide-area deployment phased-array feed...
We have measured the Faraday rotation toward a large sample of polarized radio sources behind Large Magellanic Cloud (LMC) to determine structure this galaxy's magnetic field. The field LMC consists coherent axisymmetric spiral strength approximately 1 microgauss. Strong fluctuations in are also seen on small (<0.5 parsec) and (approximately 100 parsecs) scales. bursts recent star formation supernova activity argue against standard dynamo theory, adding growing evidence for rapid...
A new polarization survey of the northern sky at 1.41 GHz is presented. The observations were carried out using 25.6 m telescope Dominion Radio Astrophysical Observatory in Canada, with an angular resolution . data are corrected for ground radiation to obtain Stokes U and Q maps on a well-established intensity scale tied absolute determinations zero levels, containing emission structures large extent, rms noise 12 mK. Survey by drift scanning between -29° +90° declination. fully sampled...
The North Polar Spur (NPS) is the brightest filament of Loop I, a large circular feature in radio continuum sky. In this paper, model consisting two synchrotron emitting shells presented that reproduces large-scale structures revealed by recent polarization surveys. polarized emission NPS reproduced one these shells. other shell, which passes close to Sun, gives rise towards Galactic poles. It proposed X-ray seen produced interaction Two OB-associations coincide with centers A formation...
We present a mosaic image of the 1.4GHz radio continuum emission from Large Magellanic Cloud (LMC) observed with Australia Telescope Compact Array (ATCA) and Parkes Telescope. The covers 10.8 x 12.3 square degrees an angular resolution 40", corresponding to spatial scale 10pc in LMC. final is suitable for studying on all scales between 40" surveyed area. In this paper, we discuss i) characteristics LMC's diffuse compact emission, ii) fraction produced by thermal processes implied star...
We present a study of the magnetic field Large Magellanic Cloud (LMC), carried out using diffuse polarized synchrotron emission data at 1.4 GHz acquired Parkes Radio Telescope and Australia Compact Array. The observed is likely to originate above LMC disk on near side galaxy. Consistent negative rotation measures (RMs) derived from indicate that line-of-sight in LMC's near-side halo directed coherently away us. In combination with RMs extragalactic sources lie behind galaxy, we show large...
(abridged) We run a Faraday structure determination data challenge to benchmark the currently available algorithms including synthesis (previously called RM in literature), wavelet, compressive sampling and $QU$-fitting. The frequency set is similar POSSUM/GALFACTS with 300 MHz bandwidth from 1.1 1.4 GHz. define three figures of merit motivated by underlying science: a) an average weighted polarized intensity, RMwtd, b) separation $\Delta\phi$ two components c) reduced chi-squared. Based on...
We present radio continuum and polarization images of the North Polar Spur (NPS) from Global Magneto-Ionic Medium Survey (GMIMS) conducted with Dominion Radio Astrophysical Observatory 26-m Telescope. fit angle versus wavelength squared over 2048 frequency channels 1280 to 1750 MHz obtain a Faraday Rotation Measure (RM) map NPS. Combining this RM published depth entire Galaxy in direction, we derive introduced by NPS Galactic interstellar medium (ISM) front behind The contributed is close...
Abstract Faraday rotation occurs along every line of sight in the Galaxy; measure (RM) synthesis allows a 3D representation interstellar magnetic field. This study uses data from Global Magneto-Ionic Medium Survey, combination single-antenna spectro-polarimetric studies, including northern sky Dominion Radio Astrophysical Observatory (DRAO) 26 m telescope (1270–1750 MHz) and southern Parkes 64 (300–480 MHz). From synthesized spectral cubes we compute zeroth, first, second moments to find...
Context: Observations of polarized emission are a significant source information on the magnetic field that pervades Interstellar Medium Galaxy. Despite acknowledged importance in interstellar processes, our knowledge configurations all scales is seriously limited. Aims: This paper describes an extensive survey Galactic at 1.4 GHz provides data with arcminute resolution and complete coverage structures from broadest angular to limit, giving magneto-ionic medium over wide range environments....
Rotation measures of pulsars and extragalactic point sources have been known to reveal large-scale antisymmetries in the Faraday rotation sky with respect Galactic plane halo that interpreted as signatures mean magnetic field halo. We describe measurements diffuse polarized radio emission over a large region northern hemisphere. Through application Measure Synthesis we achieve sensitive maps high angular resolution, capable revealing fine-scale structures about 1 deg sky. Our analysis...
The construction of the seven-dish Karoo Array Telescope (KAT-7) array in region Northern Cape South Africa was intended primarily as an engineering prototype for technologies and techniques applicable to MeerKAT telescope. This paper looks at main scientific highlights from this effort, discusses their applicability both other next-generation radio telescopes. In particular, we found that composite dish surface works well, but it becomes complicated fabricate a lacking circular symmetry;...
Radio polarimetry at decimetre wavelengths is the principal source of information on Galactic magnetic field. The diffuse polarized emission strongly influenced by Faraday rotation in magneto-ionic medium and measure prime quantity interest, implying that all Stokes parameters must be measured over wide frequency bands with many channels. DRAO 26-m Telescope has been equipped a wideband feed, polarization transducer to deliver both hands circular polarization, receiver, operating from 1277...
Sharpless 2-27 (Sh2-27) is a nearby ${\rm H\,{\small II}}$ region excited by $\zeta$Oph. We present observations of polarized radio emission from 300 to 480$\,$MHz towards Sh2-27, made with the Parkes 64$\,$m Radio Telescope as part Global Magneto-Ionic Medium Survey. These have an angular resolution $1.35^{\circ}$, and data are uniquely sensitive magneto-ionic structure on large scales. demonstrate that background Sh2-27 totally depolarized in our observations, allowing us investigate...
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,...
The Fan Region is one of the dominant features in polarized radio sky, long thought to be a local (distance < 500 pc) synchrotron feature. We present 1.3-1.8 GHz continuum observations region from Global Magneto-Ionic Medium Survey (GMIMS) and compare them maps Halpha intensity 0.408-353 GHz. high-frequency (> 1 GHz) low-frequency (< 600 MHz) emission have different morphologies, suggesting physical origin. Portions 1.5 are depolarized by about 30% ionized gas structures Perseus Arm,...
Polarization observations at and towards the local Taurus molecular cloud complex were made with Effelsberg 100-m telescope. Highly structured, frequency-dependent polarized emission features detected. We discuss polarization minima excessive rotation measures located boundaries of clouds. These get less pronounced higher frequencies. The multi-frequency data have been successfully modeled by considering magneto-ionic Faraday screens surface rotated background adds to foreground these in a...
The Galactic interstellar medium hosts a significant magnetic field, which can be probed through the synchrotron emission produced from its interaction with relativistic electrons. Linearly polarized is generated throughout Galaxy, and at longer wavelengths, modified along nearly every path by Faraday rotation in intervening magneto-ionic medium. Full characterization of requires wideband observations many frequency channels. We have surveyed radio Northern sky over range 1280-1750 MHz,...
Abstract The Global Magneto-Ionic Medium Survey (GMIMS) is a project to map the diffuse polarized emission over entire sky, Northern and Southern hemispheres, from 300 MHz 1.8 GHz. With an angular resolution of 30–60 arcmin frequency 1 or better, GMIMS will provide first spectro-polarimetric data set large-scale observed with single-dish telescopes. invaluable resource for studies magneto-ionic medium Galaxy in local disk, halo, its transition.
Much data on the Galactic polarized radio emission has been gathered in last five decades. All-sky surveys have made, but only narrow, widely spaced frequency bands, and are inadequate for characterization of Faraday rotation, main determinant appearance sky at decimetre wavelengths. We describe a survey from Southern sky, aiming to characterize magneto-ionic medium, particularly strength configuration magnetic field. This work is part Global Magneto-Ionic Medium Survey (GMIMS). designed...
Faraday tomography of broadband radio polarization surveys enables us to study magnetic fields and their interaction with the interstellar medium (ISM). Such include Global Magneto-Ionic Medium Survey (GMIMS), which covers northern southern hemispheres at sim 300--1800 MHz. In this work, we used GMIMS High Band South (1328--1768 MHz), also named Southern Twenty-centimeter All-sky Polarization (STAPS), observes sky a resolution 18arcmin . To extract key parameters magnetized ISM from STAPS,...
We present 1420 MHz polarization images of a 5x5 degree region around the planetary nebula (PN) DeHt 5. The reveal narrow Faraday-rotation structures on visible disk 5, as well two wider, tail-like, "behind" Though 5 is an old PN known to be interacting with interstellar medium (ISM), tail has not previously been identified for this object. innermost approximately 3 pc long and runs away from north-east edge in direction roughly opposite that sky-projected space velocity white dwarf central...
We present a new method of determining the systemic velocity Galactic supernova remnants (SNRs) based on H I absorption their linearly polarized radio continuum emission. Conventional observations total power emission are limited by and self-absorption along line sight, but since is unpolarized, only limits measurements noise resolution. This leads to lower uncertainties makes it possible obtain profiles for virtually all SNRs with very precise column densities. To demonstrate technique, we...