A NEW MODEL OF THE GALACTIC MAGNETIC FIELD

A new, much-improved model of the Galactic magnetic field (GMF) is presented. We use the WMAP7 Galactic synchrotron emission map and more than 40,000 extragalactic rotation measures to constrain the parameters of the GMF model, which is substantially generalized compared with earlier work to now inc...

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Bibliographic Details
Published in:The Astrophysical journal 2012-09, Vol.757 (1), p.1-13
Main Authors: JANSSON, Ronnie, FARRAR, Glennys R
Format: Article
Language:English
Subjects:
ASTRONOMY
ASTROPHYSICS
ASTROPHYSICS, COSMOLOGY AND ASTRONOMY
COSMIC ELECTRONS
Earth, ocean, space
ELECTRON DENSITY
Emission
Exact sciences and technology
Galactic rotation
GALAXIES
Halos
INTERSTELLAR MAGNETIC FIELDS
Magnetic fields
Mathematical models
MILKY WAY
ROTATION
SYNCHROTRON RADIATION
Synchrotrons
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Summary:A new, much-improved model of the Galactic magnetic field (GMF) is presented. We use the WMAP7 Galactic synchrotron emission map and more than 40,000 extragalactic rotation measures to constrain the parameters of the GMF model, which is substantially generalized compared with earlier work to now include an out-of-plane component (as suggested by observations of external galaxies) and striated-random fields (motivated by theoretical considerations). The new model provides a greatly improved fit to observations. Consistent with our earlier analyses, the best-fit model has a disk field and an extended halo field. Our new analysis reveals the presence of a large, out-of-plane component of the GMF; as a result, the polarized synchrotron emission of our Galaxy seen by an edge-on observer is predicted to look intriguingly similar to what has been observed in external edge-on galaxies. We find evidence that the cosmic-ray electron density is significantly larger than given by GALPROP or else that there is a widespread striated component to the GMF.
ISSN:0004-637X
1538-4357
DOI:10.1088/0004-637X/757/1/14