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arXiv · 0812.3673

The magnetic field structure in NGC 253 in presence of a galactic wind

V. Heesen·M. Krause·R. Beck·R. -J. Dettmar
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Abstract

We present radio continuum polarimetry observations of the nearby edge-on galaxy NGC 253 which possesses a very bright radio halo. Using the vertical synchrotron emission profiles and the lifetimes of cosmic-ray electrons, we determined the cosmic-ray bulk speed as (300+/-30) km/s, indicating the presence of a galactic wind in this galaxy. The large-scale magnetic field was decomposed into a toroidal axisymmetric component in the disk and a poloidal component in the halo. The poloidal component shows a prominent X-shaped magnetic field structure centered on the nucleus, similar to the magnetic field observed in other edge-on galaxies. Faraday rotation measures indicate that the poloidal field has an odd parity (antisymmetric). NGC 253 offers the possibility to compare the magnetic field structure with models of galactic dynamos and/or galactic wind flows.

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V. Heesen, M. Krause, R. Beck, R. -J. Dettmar. 2008-12-18. The magnetic field structure in NGC 253 in presence of a galactic wind. https://doi.org/10.1017/s1743921309031184

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