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Antisymmetry in the Faraday Rotation sky caused by a nearby magnetized bubble

Lookup NU author(s): Dr Andrew Fletcher

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Abstract

Rotation measures (RMs) of pulsars and extragalactic point sources have been known to reveal large-scale antisymmetries in the Faraday rotation sky with respect to the Galactic plane and halo that have been interpreted as signatures of the mean magnetic field in the Galactic halo. We describe Faraday rotation measurements of the diffuse Galactic polarized radio emission over a large region in the northern Galactic hemisphere. Through application of RM synthesis we achieve sensitive Faraday rotation maps with high angular resolution, capable of revealing fine-scale structures of ~1° in the Faraday rotation sky. Our analysis suggests that the observed antisymmetry in the Faraday rotation sky at b>0° is dominated by the magnetic field around a local H I bubble at a distance of 100 pc, and not by the magnetic field of the Galactic halo. We derive physical properties of the magnetic field of this shell, which we find to be 20-34 μG strong. It is clear that the diffuse polarized radio emission contains important information about the local magneto-ionic medium, which cannot yet be derived from Faraday RMs of extragalactic sources or pulsars alone.

Publication metadata

Author(s): Wolleben M, Fletcher A, Landecker T, Carretti E, Dickey JM, Gaensler B, Haverkorn M, McClure-Griffiths N, Reich W, Taylor RA

Publication type: Article

Publication status: Published

Journal: Astrophysical Journal Letters

Year: 2010

Volume: 724

Issue: 1

Pages: L48-L52

Print publication date: 28/10/2010

ISSN (print): 2041-8205

ISSN (electronic): 2041-8213

Publisher: IOP Publishing Ltd

URL: http://dx.doi.org/10.1088/2041-8205/724/1/L48

DOI: 10.1088/2041-8205/724/1/L48

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