| Type |
Journal Article |
| Names |
S. A. Mao, B. M. Gaensler, M. Haverkorn, E. G. Zweibel, G. J. Madsen, N. M. McClure-Griffiths, A. Shukurov, P. P. Kronberg |
| Publication |
The Astrophysical Journal |
| Volume |
714 |
| Issue |
2 |
| Pages |
1170-1186 |
| Date |
May 1, 2010 |
| Short Title |
A Survey of Extragalactic Faraday Rotation at High Galactic Latitude |
| URL |
http://adsabs.harvard.edu/abs/2010ApJ...714.1170M |
| Library Catalog |
NASA ADS |
| Abstract |
We present a study of the vertical magnetic field of the Milky Way
toward the Galactic poles, determined from observations of Faraday
rotation toward more than 1000 polarized extragalactic radio sources at
Galactic latitudes |b| >= 77°, using the Westerbork Radio
Synthesis Telescope and the Australia Telescope Compact Array. We find
median rotation measures (RMs) of 0.0 ± 0.5 rad
m-2 and +6.3 ± 0.7 rad m-2
toward the north and south Galactic poles, respectively, demonstrating
that there is no coherent vertical magnetic field in the Milky Way at
the Sun's position. If this is a global property of the Milky Way's
magnetism, then the lack of symmetry across the disk rules out pure
dipole or quadrupole geometries for the Galactic magnetic field. The
angular fluctuations in RM seen in our data show no preferred scale
within the range ≈0fdg1 to ≈25°. The observed standard
deviation in RM of ~9 rad m-2 then implies an upper
limit of ~1 μG on the strength of the random magnetic field in the
warm ionized medium at high Galactic latitudes. |
| Tags |
Galaxy: halo, ISM: magnetic fields, Polarization |