Zooming into the heart of a double-double radio galaxy with the EVN and e-MERLIN

The radio source J0028+0035 is a recently discovered double-double radio galaxy at redshift z=0.398. The relic outer lobes are separated by about 1.1 Mpc while the collinear inner lobes span less than 100 kpc projected onto the sky. In the arcsec-resolution radio images, there is also a central radio feature that offers the intriguing possibility of being resolved into a pc-scale, third pair of innermost lobes. This would make J0028+0035 a rare triple-double source where traces of three distinct episodes of radio activity could be observed. To reveal the compact radio structure of the central component, we conducted observations with the European VLBI Network (EVN) and the enhanced Multi-Element Remotely Linked Interferometer Network (e-MERLIN). Here we present our high-resolution 1.7-GHz image of the core in J0028+0035 that consists of a single mJy-level component. As a bonus, a nearby compact radio source, 5BZU J0028+0035, a coincident object seen in the background, with an angular separation of only ∼15 arcsec from our
primary target was also studied by employing multi-phase-centre correlation.