Universität zu Köln

Ma, Yik Ki ORCID: 0000-0003-0742-2006, Mao, S. A., Stil, Jeroen, Basu, Aritra ORCID: 0000-0003-2030-3394, West, Jennifer, Heiles, Carl, Hill, Alex S. and Betti, S. K. (2019). A broad-band spectro-polarimetric view of the NVSS rotation measure catalogue I. Breaking the n pi-ambiguity. Mon. Not. Roy. Astron. Soc., 487 (3). S. 3432 - 3454. OXFORD: OXFORD UNIV PRESS. ISSN 1365-2966

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Abstract

The NRAO VLA Sky Survey (NVSS) rotation measure (RM) catalogue is invaluable for the study of cosmic magnetism, However, the RM values reported in it can be affected by n: r ambiguity, resulting in deviations of the reported RM from the true values by multiples of 652.9 rad in 2, We therefore set off to observationally constrain the fraction of sources in the RM catalogue affected by this ambiguity. New broad-band spectro-polarimetric observations were performed with the Karl G, Jansky Very Large Array (VLA) at 1-2 GH.z, with 23 n7 ambiguity candidates selected by their peculiarly high IRMI values. We identified nine sources with erroneous RM values due to T/7-ambiguity and 11 with reliable RM values, In addition, we found two sources to be unpolarized and one source to be inconsistent with neither rrr ambiguity nor reliable RM cases. By comparing the statistical distributions of the above two main classes, we devised a measure of how much a source's RM deviates from that of its neighbours: A/o-, which we found to be a good diagnostic of 1.77-ambiguity. With this, we estimate that there are at least 50 sources affected by run,-ambiguity among the 37 543 sources in the catalogue. Finally, we explored the Faraday complexities of our sources revealed by our broad-band observations.

Item Type:	Journal Article
Creators:	Creators Email ORCID ORCID Put Code Ma, Yik Ki UNSPECIFIED orcid.org/0000-0003-0742-2006 UNSPECIFIED Mao, S. A. UNSPECIFIED UNSPECIFIED UNSPECIFIED Stil, Jeroen UNSPECIFIED UNSPECIFIED UNSPECIFIED Basu, Aritra UNSPECIFIED orcid.org/0000-0003-2030-3394 UNSPECIFIED West, Jennifer UNSPECIFIED UNSPECIFIED UNSPECIFIED Heiles, Carl UNSPECIFIED UNSPECIFIED UNSPECIFIED Hill, Alex S. UNSPECIFIED UNSPECIFIED UNSPECIFIED Betti, S. K. UNSPECIFIED UNSPECIFIED UNSPECIFIED
URN:	urn:nbn:de:hbz:38-133773
DOI:	10.1093/mnras/stz1325
Journal or Publication Title:	Mon. Not. Roy. Astron. Soc.
Volume:	487
Number:	3
Page Range:	S. 3432 - 3454
Date:	2019
Publisher:	OXFORD UNIV PRESS
Place of Publication:	OXFORD
ISSN:	1365-2966
Language:	English
Faculty:	Unspecified
Divisions:	Unspecified
Subjects:	no entry
Uncontrolled Keywords:	Keywords Language COHERENT MAGNETIC-FIELD; FARADAY DEPTH STRUCTURE; REFERENCE FRAME SOURCES; ASTROMETRIC SUITABILITY; VLBA OBSERVATIONS; RADIO GALAXIES; SKY; POLARIZATION; DEPOLARIZATION; CLUSTERS Multiple languages Astronomy & Astrophysics Multiple languages
Refereed:	Yes
URI:	http://kups.ub.uni-koeln.de/id/eprint/13377