http://arxiv.org/abs/1809.07528
The popular JF12 analytic model by Jansson & Farrar (2012) provides a quantitative description of the Galaxy’s large-scale magnetic field that is widely used in various astrophysical applications. However, both the poloidal X-type component and the spiral disk component of JF12 exhibit regions in which the magnetic divergence constraint is severely violated. We first propose a cure for this problem, resulting in a truly solenoidal large-scale field. Second, the otherwise straight field lines of the X-type component exhibit kinks in the Galactic plane that, in addition to implying the presence of a singular current sheet, may pose difficulties for, e.g., numerical tracing of cosmic-ray particles. We propose and discuss two possible strategies to mitigate this problem. All corrections are kept as minimal as possible in order not to destroy the agreement to observational data that the unmodified JF12 field is based on. Furthermore, the performance of our improved version of the field model is quantitatively assessed by test simulations using the CRPropa Galactic cosmic-ray propagation code.
J. Kleimann, T. Schorlepp, L. Merten, et. al.
Fri, 21 Sep 18
6/63
Comments: 10 pages, 6 figures
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