The jet paths of radio active galactic nuclei and their cluster weather

Abstract

We studied bent radio sources within X-ray galaxy groups in the COSMOS and XMM-LSS fields. The radio data were obtained from the MeerKAT International GHz Tiered Extragalactic Explorations data release 1 (MIGHTEE-DR1) at 1.2-1.3 GHz, with angular resolutions of 8.9″ and 5″, and median noise levels of rmsmed ∼= 3.5 and 5.5 μJy/beam. Bent radio active galactic nuclei (AGN) were identified through visual inspection. Our analysis included 19 bent radio AGN in the COSMOS field and 17 in the XMM-LSS field that lie within X-ray galaxy groups (2 × 1013 ≲ M200c/M⊙ ≤ 3×1014). We investigated the relationship between their bending angle (BA) - the angle formed by the jets or lobes of two-sided radio sources associated with AGN - and the properties of their host galaxies and large-scale environment probed by the X-ray galaxy groups. Our key findings are: (a) In the XMM-LSS field, we observed a strong correlation between the linear projected size of the bent AGN, the group halo mass, and the projected distance from the group centre. This trend, consistent with previous studies, was not detected in the COSMOS sample. (b) The BA is a function of environmental density, with the type of medium playing a significant role. Additionally, at z ≤ 0.5 we found a higher number of bent sources (BA ≤ 160°) compared to higher redshifts (z ∼ 1), by a factor of >1.5. This trend aligns with magneto-hydrodynamic simulations, which suggest that denser environments and longer interaction times at lower redshifts contribute to this effect. A comparison with the literature suggests that jet bending in galaxy groups within the redshift range 0.1 < z < 1.2 is primarily driven by ram pressure exerted on the jets, which occurs during quiescent phases of AGN activity. This study underscores the role of environmental interactions in shaping the morphology of radio AGN within galaxy groups, providing insights into the interplay between large-scale structure and AGN physics.