LOFAR image of the 12 sources in the sample at 144 MHz. Each source is overlaid with the half light radius in the r band of its host galaxy (white circle) taken from Kim et al. (2014) The pink arrow marks the direction and physical distance towards the centre of the Virgo cluster (NGC 4486). The ellipse in the lower left corner indicates the beam size 9″ × 5″ for all images with the exception of NGC 4472 and NGC 4649. Here, the ellipse indicates a beam size of 20″ × 20″ as the low-resolution LOFAR images are plotted.