COMPARISON OF ALGORITHMS FOR DETERMINATION OF ROTATION MEASURE AND FARADAY STRUCTURE. I. 1100–1400 MHZ

DOI DOI Web Site Web Site 研究データあり 被引用文献10件 参考文献53件 オープンアクセス

書誌事項

公開日
2015-01-19
資源種別
journal article
権利情報
  • http://iopscience.iop.org/info/page/text-and-data-mining
  • http://iopscience.iop.org/page/copyright
DOI
  • 10.1088/0004-6256/149/2/60
  • 10.48550/arxiv.1409.4151
公開者
American Astronomical Society

説明

(abridged) We run a Faraday structure determination data challenge to benchmark the currently available algorithms including Faraday synthesis (previously called RM synthesis in the literature), wavelet, compressive sampling and $QU$-fitting. The frequency set is similar to POSSUM/GALFACTS with a 300 MHz bandwidth from 1.1 to 1.4 GHz. We define three figures of merit motivated by the underlying science: a) an average RM weighted by polarized intensity, RMwtd, b) the separation $����$ of two Faraday components and c) the reduced chi-squared. Based on the current test data of signal to noise ratio of about 32, we find that: (1) When only one Faraday thin component is present, most methods perform as expected, with occasional failures where two components are incorrectly found; (2) For two Faraday thin components, QU-fitting routines perform the best, with errors close to the theoretical ones for RMwtd, but with significantly higher errors for $����$. All other methods including standard Faraday synthesis frequently identify only one component when $����$ is below or near the width of the Faraday point spread function; (3) No methods, as currently implemented, work well for Faraday thick components due to the narrow bandwidth; (4) There exist combinations of two Faraday components which produce a large range of acceptable fits and hence large uncertainties in the derived single RMs; in these cases, different RMs lead to the same Q, U behavior, so no method can recover a unique input model.

15 pages, 8 figures, 5 tables, accepted by AJ. Some figures have been degraded, for a full resolution version, see http://physics.usyd.edu.au/~xhsun/datachallengeI.pdf

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