cuFFS: A GPU-accelerated code for Fast Faraday rotation measure Synthesis

Sridhar, S. S.; Heald, G.; Hulst, J. M. van der

doi:10.1016/j.ascom.2018.10.002

Cited by 7 publications

(6 citation statements)

References 35 publications

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“…We then performed RM synthesis (e.g., Burn 1966;Brentjens & de Bruyn 2005) using the Compute Unified Device Architectureaccelerated Fast Faraday Synthesis (cuFFS; Sridhar, Heald, & van der Hulst 2018) software. As presented by Brentjens & de Bruyn (2005), the key parameters for RM synthesis-the RM resolution ( (RM)), maximum RM (|RM max |), and maximum scale in RM space (max.scale)-are defined as…”

Section: Data Reductionmentioning

confidence: 99%

The POlarised GLEAM Survey (POGS) II: Results from an all-sky rotation measure synthesis survey at long wavelengths

Riseley

Galvin

Sobey

et al. 2020

Publ. Astron. Soc. Aust.

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The low-frequency linearly polarised radio source population is largely unexplored. However, a renaissance in low-frequency polarimetry has been enabled by pathfinder and precursor instruments for the Square Kilometre Array. In this second paper from the POlarised GaLactic and Extragalactic All-Sky MWA Survey-the POlarised GLEAM Survey, or POGS-we present the results from our all-sky MWA Phase I Faraday Rotation Measure survey. Our survey covers nearly the entire Southern sky in the Declination range $-82^\circ$ to $+30^\circ$ at a resolution between around three and seven arcminutes (depending on Declination) using data in the frequency range 169−231 MHz. We have performed two targeted searches: the first covering 25 489 square degrees of sky, searching for extragalactic polarised sources; the second covering the entire sky South of Declination $+30^\circ$ , searching for known pulsars. We detect a total of 517 sources with 200 MHz linearly polarised flux densities between 9.9 mJy and 1.7 Jy, of which 33 are known radio pulsars. All sources in our catalogues have Faraday rotation measures in the range $-328.07$ to $+279.62$ rad m−2. The Faraday rotation measures are broadly consistent with results from higher-frequency surveys, but with typically more than an order of magnitude improvement in the precision, highlighting the power of low-frequency polarisation surveys to accurately study Galactic and extragalactic magnetic fields. We discuss the properties of our extragalactic and known-pulsar source population, how the sky distribution relates to Galactic features, and identify a handful of new pulsar candidates among our nominally extragalactic source population.

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Section: Data Reductionmentioning

confidence: 99%

The POlarised GLEAM Survey (POGS) II: Results from an all-sky rotation measure synthesis survey at long wavelengths

Riseley

Galvin

Sobey

et al. 2020

Publ. Astron. Soc. Aust.

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“…We used the new GPU-based cuFFS recipe b (Sridhar et al 2018) to perform RM synthesis on our mosaicked frequency cubes (each of which covers approximately 2 400-3 000 deg 2 of sky). cuFFS has been optimised for processing large data cubes on GPU-based systems, primarily for processing LOFAR polarimetric data.…”

Section: Rm Synthesismentioning

confidence: 99%

The POlarised GLEAM Survey (POGS) I: First results from a low-frequency radio linear polarisation survey of the southern sky

Riseley

Lenc

Eck

et al. 2018

Publ. Astron. Soc. Aust.

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The low-frequency polarisation properties of radio sources are poorly studied, particularly in statistical samples. However, the new generation of low-frequency telescopes, such as the Murchison Widefield Array (MWA; the precursor for the low-frequency component of the Square Kilometre Array) offers an opportunity to probe the physics of radio sources at very low radio frequencies. In this paper, we present a catalogue of linearly-polarised sources detected at 216 MHz, using data from the Galactic and Extragalactic All-sky MWA (GLEAM) survey. Our catalogue covers the Declination range −17 • to −37 • and 24 hours in Right Ascension, at a resolution of around 3 arcminutes. We detect 81 sources (including both a known pulsar and new pulsar candidate) with linearly-polarised flux densities in excess of 18 mJy across a survey area of approximately 6400 square degrees, corresponding to a surface density of 1 source per 79 square degrees. The level of Faraday rotation measured for our sources is broadly consistent with those recovered at higher frequencies, with typically more than an order of magnitude improvement in the uncertainty compared to higher-frequency measurements. However, our catalogue is likely incomplete at low Faraday rotation measures, due to our practice of excluding sources in the region where instrumental leakage appears. The majority of sources exhibit significant depolarisation compared to higher frequencies; however, a small sub-sample repolarise at 216 MHz. We also discuss the polarisation properties of four nearby, large-angular-scale radio galaxies, with a particular focus on the giant radio galaxy ESO 422−G028, in order to explain the striking differences in polarised morphology between 216 MHz and 1.4 GHz.

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“…For example, RM Synthesis needs O(N 2 ) calculations if the discrete FT is used, or O(N log 2 N) if the Fast FT is used (e.g., [15]), where N is the number of frequency channels in the observation. A more detailed analysis and the opportunities presented by GPU acceleration are presented by Sridhar et al [16]. RM CLEAN involves an iterative loop for subtracting the factor-multiplied RMSF fromF(φ), and thus the computational cost is O (N × N CLEAN ), where N CLEAN is the number of required RM CLEAN iterations.…”

Section: Comparison Of Methodsmentioning

confidence: 99%

Faraday Tomography Tutorial

2018

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The capabilities of wide-band polarization datasets that are now becoming available from precursors/pathfinders to the Square Kilometre Array (SKA), and eventually from the SKA itself, make it possible to use the Faraday tomography technique to facilitate the study of cosmic magnetism. While many programs enabling Faraday tomography have been developed by various authors and it is now becoming easier to apply the required techniques, the interpretation of the results is not straightforward. This is not only because of the lack of a one-to-one relation between the Faraday depth and the physical depth, and observational artifacts such as instrumental polarization, but also because the choice of the method that is used and its settings can be reflected in the results. Thus, it is essential to understand how the various methods enabling Faraday tomography are suited for the efficient application of the technique. In the workshop “The Power of Faraday Tomography”, we organized a Faraday tomography tutorial to help the participants understand the required tools. In this article, we summarize the basics of the techniques, and provide an overview of the tutorial.

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cuFFS: A GPU-accelerated code for Fast Faraday rotation measure Synthesis

Cited by 7 publications

References 35 publications

The POlarised GLEAM Survey (POGS) II: Results from an all-sky rotation measure synthesis survey at long wavelengths

The POlarised GLEAM Survey (POGS) II: Results from an all-sky rotation measure synthesis survey at long wavelengths

The POlarised GLEAM Survey (POGS) I: First results from a low-frequency radio linear polarisation survey of the southern sky

Faraday Tomography Tutorial

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