Non-thermal emission and magnetic fields in nearby galaxies

Magnetic fields in galaxies can be detected and studied by mapping the radio emission produced by cosmic ray electrons as they accelerate along the field lines in the interstellar medium. By observing galaxies at low radio frequencies (in the metre-wavelength regime), we can detect electromagnetic radiation produced by old populations of electrons which can propagate to the far reaches/outskirts of the galaxy. However, previous low-frequency observations of nearby galaxies are largely limited by their low sensitivity (unable to detect faint, diffuse emission) and poor angular resolution (unable to differentiate between sources). In this thesis, I have observed and studied a sample of nearby galaxies to map the magnetic field strength in them. These galaxies were observed using two radio telescopes operated from the Netherlands (the Low Frequency Array (LOFAR) and the Westerbork Synthesis Radio Telescope) both of which offer improved sensitivity and better angular resolution than previous studies.

Dissertation: http://hdl.handle.net/11370/ddfc9ecc-edca-4322-9d10-1b95cc3d1d2d