Monday, 13th April at 2.00pm at the JAC
Volker Heesen
Univ. Hertfordshire
"The magnetic field structure in NGC 253 -
in the presence of a galactic wind"
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 km/s, indicating the presence of a galactic wind in this
galaxy. The large-scale magnetic field was decomposed into a spiral
magnetic field in the disk and a halo component. This halo 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 halo 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.
Related papers:
Cosmic rays and the magnetic field in the nearby starburst galaxy NGC 253,
Heesen, V.; Beck, R.; Krause, M.; Dettmar, R.-J., 2009, A&A, 494, 563
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