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Lookup NU author(s): Professor Anvar Shukurov
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We present a study of the Milky Way disk and halo magnetic field, determined from observations of Faraday rotation measure (RM) toward 641 polarized extragalactic radio sources in the Galactic longitude range 100 degrees-117 degrees, within 30 degrees of the Galactic plane. For vertical bar b vertical bar < 15 degrees, we observe a symmetric RM distribution about the Galactic plane. This is consistent with a disk field in the Perseus arm of even parity across the Galactic mid-plane. In the range 15 degrees < vertical bar b vertical bar < 30 degrees, we find median RMs of -15 +/- 4 rad m(-2) and -62 +/- 5 rad m(-2) in the northern and southern Galactic hemispheres, respectively. If the RM distribution is a signature of the large-scale field parallel to the Galactic plane, then this suggests that the halo magnetic field toward the outer Galaxy does not reverse direction across the mid-plane. The variation of RMas a function of Galactic latitude in this longitude range is such that RMs become more negative at larger vertical bar b vertical bar. This is consistent with an azimuthal magnetic field of strength 2 mu G (7 mu G) at a height 0.8-2 kpc above (below) the Galactic plane between the local and the Perseus spiral arm. We propose that the Milky Way could possess spiral-like halo magnetic fields similar to those observed in M51.
Author(s): Mao SA, McClure-Griffiths NM, Gaensler BM, Brown JC, van Eck CL, Haverkorn M, Kronberg PP, Stil JM, Shukurov A, Taylor AR
Publication type: Article
Publication status: Published
Journal: Astrophysical Journal
Print publication date: 23/07/2012
ISSN (print): 0004-637X
ISSN (electronic): 1538-4357
Publisher: Institute of Physics Publishing, Inc.
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