2020MNRAS.495.4237M

We investigate the connection between X-ray and radio-loud active galactic nuclei (AGNs) and the physical properties of their evolved and massive host galaxies, focussing on the mass-related quenching channel followed by M^*(≃10^10.6 M_☉) galaxies in the rest-frame NUV-r versus r-K (NUVrK) colour diagram at 0.2 < z < 0.5. While our results confirm that (1) radio-loud AGNs are predominantly hosted by already-quenched and very massive (M_*>10¹¹ M_☉) galaxies, ruling out their feedback as a primary driver of M^* galaxy quenching, we found that (2) X-ray AGNs affected by heavy obscuration of their soft X-ray emission are mostly hosted by M^* galaxies that are in the process of quenching. This is consistent with a quenching scenario that involves mergers of (gas-poor) M^* galaxies after the onset of the quenching process, i.e. a scenario where M^* galaxy mergers are not the cause but rather an aftermath of the quenching mechanism(s). In that respect, we discuss how our results may support a picture where the slow quenching of M^* galaxies happens due to halo-halo mergers along cosmic filaments.