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 \pm 30 km s ^ { -1 } , 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 .