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24th of January 2017
Resolved magnetic structures in the disk-halo interface of NGC 628
by George Heald (CASS)
Spiral galaxies host large-scale magnetic fields that evolve over millions of years via turbulence in the Interstellar Medium and the rotation of the galaxy itself. These galactic-sized magnetic fields contain an ordered component, primarily located in the regions between the spiral arms, where randomness imposed by the star formation process is low. Such ordered magnetic fields and their directionality can be efficiently observed with cm-wavelength radio synchrotron radiation, and its degree of linear polarisation. The above picture shows an optical image of the face-on spiral galaxy NGC628 as observed with the Calar Alto 1.23-m telescope in Spain, superimposed with flow lines showing the direction of the ordered large-scale magnetic field as observed with the Jansky Very Large Array (JVLA) at radio frequencies between 2-4 GHz. The image is presented as part of new work by a team including George Heald (CASS) that was recently accepted for publication. The research also found evidence for two drivers of magnetic turbulence in the disk-halo region of NGC 628, namely, Parker instabilities and superbubbles.

Reference: Mulcahy, Beck, and Heald (2017), A&A, accepted (arXiv)

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