Giant radio sources, including galaxies and quasars (hereafter GRGs), are active galactic nuclei (AGN) hosting relativistic jets with source sizes exceeding the projected length of 700 kilo-parsecs (roughly the distance from the Milky Way to the Andromeda galaxy!). They are crucial to understanding the evolution of radio sources and their interaction with the surrounding environment. Some of these enigmatic objects, have also been reported as gamma-ray emitters based on data from the Fermi gamma-ray satellite. Since GRGs are thought to be aligned close to the plane of the sky, they are invaluable targets to explore the radiative mechanisms responsible for the observed gamma-ray emission.

Paliya et al. have carried out a systematic search of gamma-ray emitting GRGs using sensitive low-resolution radio surveys, including the Rapid ASKAP Continuum Survey. They have identified 16 gamma-ray emitting GRGs, with 8 of these, including PMN J0525-2010, being reported as GRGs for the first time. GRGs usually have a relatively steep radio spectrum, however most of the gamma-ray emitting GRGs exhibit a flat or inverted radio spectrum. Since these objects are gamma-ray emitters, they might be viewed at a relatively small viewing angle compared to the general, non-gamma-ray detected GRG population, leading to the observation of a flatter radio spectrum. The image above shows the RACS radio morphology of PMN J0525-2010, associated with 4FGL J0525.6-2008 The beam size is shown in the bottom left corner, and the cross marks the positions of the optical object.