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Antisymmetry in the faraday rotation sky caused by a nearby magnetized bubble

journal contribution
posted on 2023-05-17, 03:24 authored by Wolleben, M, Fletcher, A, Landecker, L, Carretti, E, John DickeyJohn Dickey, Gaensler, BM, Haverkorn, M, McClure-Griffiths, N, Reich, W, Taylor, AR
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 Hi 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 20–34μG 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.

History

Publication title

Astrophysical Journal

Volume

724

Pagination

L48-L52

ISSN

0004-637X

Department/School

School of Natural Sciences

Publisher

Univ Chicago Press

Place of publication

1427 E 60Th St, Chicago, USA, Il, 60637-2954

Rights statement

Copyright 2010 The American Astronomical Society

Repository Status

  • Restricted

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Expanding knowledge in the physical sciences

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