Radio observations of galactic supernova remnants

At low radio frequencies, supernova remnants (SNRs) show synchrotron emission from accelerated electrons. In the millimetre regime they can also show molecular line emission if they are associated with neighbouring molecular clouds. In this thesis we present observations from the LOw Frequency ARray (LOFAR), both from the high band and low band antennae, of three different supernova remnants: Cassiopeia A, VRO 42.05.01, and Tycho. We study the synchrotron spectrum of these sources, and in particular any deviations from its characteristic power-law behaviour which can be related to the presence of an absorbing plasma or the particle acceleration mechanism in the shock. In Cassiopeia A we find free-free emission from the ionised, cold plasma of its unchocked ejecta. In Tycho, we find absorption from ionised material that surrounds the SNR, likely overionised molecular clouds. In the case of VRO 42.05.01 we find a radio spectrum that steepens at low frequencies and that, we propose, might be related to the effective shock compression ratios electrons of different energies feel in radiative shocks. We also observed the latter source with the IRAM 30m telescope, to look for interaction between the SNR and its neighbouring molecular clouds. We find a wind-blown bubble, possibly created by the progenitor star of the VRO 42.05.01 remnant.