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Pulsar rotation measures and the large-scale structure of the galactic magnetic field

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posted on 2024-07-13, 03:40 authored by Jinlin Lin Han, Richard N. Manchester, Andrew G. Lyne, Guo Jun Qiao, W. van Straten
The large-scale magnetic field of our Galaxy can be probed in three dimensions using Faraday rotation of pulsar signals. We report on the determination of 223 rotation measures from polarization observations of relatively distant southern pulsars made using the Parkes radio telescope. Combined with previously published observations, these data give clear evidence for large-scale counterclockwise fields (viewed from the north Galactic pole) in the spiral arms interior to the Sun and weaker evidence for a counterclockwise field in the Perseus arm. However, in interarm regions, including the solar neighborhood, we present evidence that suggests that large-scale fields are clockwise. We propose that the large-scale Galactic magnetic field has a bisymmetric structure with reversals on the boundaries of the spiral arms. Streaming motions associated with spiral density waves can directly generate such a structure from an initial, inwardly directed radial field. Large-scale fields increase toward the Galactic center, with a mean value of about 2 μG in the solar neighborhood and 4 μG at a galactocentric radius of 3 kpc.

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ISSN

0004-637X

Journal title

Astrophysical Journal

Volume

642

Pagination

13 pp

Publisher

University of Chicago Press

Copyright statement

Copyright © 2006 The American Astronomical Society. is reproduced in accordance with the copyright policy of the publisher.

Language

eng

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