SIMBAD references

2019MNRAS.487.3432M - Mon. Not. R. Astron. Soc., 487, 3432-3453 (2019/August-2)

A broad-band spectro-polarimetric view of the NVSS rotation measure catalogue - I. Breaking the nπ-ambiguity.

MA Y.K., MAO S.A., STIL J., BASU A., WEST J., HEILES C., HILL A.S. and BETTI S.K.

Abstract (from CDS):

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 nπ-ambiguity, resulting in deviations of the reported RM from the true values by multiples of ±652.9 rad m–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 GHz, with 23 nπ-ambiguity candidates selected by their peculiarly high |RM| values. We identified nine sources with erroneous RM values due to nπ-ambiguity and 11 with reliable RM values. In addition, we found two sources to be unpolarized and one source to be inconsistent with neither nπ-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: Δ/σ, which we found to be a good diagnostic of nπ-ambiguity. With this, we estimate that there are at least 50 sources affected by nπ-ambiguity among the 37 543 sources in the catalogue. Finally, we explored the Faraday complexities of our sources revealed by our broad-band observations.

Abstract Copyright: © 2019 The Author(s) Published by Oxford University Press on behalf of the Royal Astronomical Society

Journal keyword(s): ISM: magnetic fields - galaxies: active - galaxies: magnetic fields - radio continuum: galaxies

Nomenclature: Table 2: [MMS2019] NVSS JHHMMSS+DDMMSSa N=10.

Simbad objects: 66

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2021.04.14-11:18:39

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