A NEW MODEL OF THE GALACTIC MAGNETIC FIELD

Abstract

A new, much improved model of the Galactic Magnetic Field (GMF) is presented.\nWe use the WMAP7 Galactic Synchrotron Emission map and more than forty thousand\nextragalactic rotation measures to constrain the parameters of the GMF model,\nwhich is substantially generalized compared to earlier work to now include an\nout-of-plane component (as suggested by observations of external galaxies) and\nstriated-random fields (motivated by theoretical considerations). The new model\nprovides a greatly improved fit to observations. Consistent with our earlier\nanalyses, the best-fit model has a disk field and an extended halo field. Our\nnew analysis reveals the presence of a large, out-of-plane component of the\nGMF; as a result, the polarized synchrotron emission of our Galaxy seen by an\nedge-on observer is predicted to look intriguingly similar to what has been\nobserved in external edge-on galaxies. We find evidence that the cosmic ray\nelectron density is significantly larger than given by GALPROP, or else that\nthere is a widespread striated component to the GMF.\n