A Morphological Identification and Study of Radio Galaxies from LoTSS DR2. III. The Multiwavelength Analysis of Winged Radio Galaxies

TL;DR

This study analyzes 621 winged radio galaxies from LoTSS DR2 across multiple wavelengths, revealing their morphological, environmental, and AGN characteristics, and exploring the physical processes shaping their X-shaped and Z-shaped structures.

Contribution

It provides the largest statistical analysis of X-shaped and Z-shaped radio galaxies, linking their morphology to jet power, environment, and merger activity.

Findings

XRGs are more radio-luminous than ZRGs.

Most WRGs are hosted by massive elliptical galaxies in moderate-density environments.

A significant fraction of XRGs show small offsets suggesting jet reorientation.

Abstract

We present a multiwavelength follow-up study of 621 winged radio galaxies (WRGs) recently identified from LoTSS DR2, constituting the largest statistically significant samples of X-shaped (XRGs) and Z-shaped (ZRGs) radio galaxies to date. Our results show that WRGs are predominantly strongly radio-dominated, with XRGs on average more radio-luminous than ZRGs. Their optical hosts are massive elliptical galaxies residing in moderate-density environments. For 270 of XRGs, we measure angular offsets between the radio wings and the optical major axis. While most XRGs show large misalignments consistent with hydrodynamic backflow along the host minor axis, a substantial fraction ($\sim$25\%) exhibits small offsets (<30{\deg}), indicating that additional processes, such as jet reorientation, may also play a role. ZRGs, in contrast, are characterized by strongly antisymmetric deformations of their radio lobes pointing toward a coherent mechanism affecting both jets, modulated by local environmental interactions at the lobe termini. Mid-infrared diagnostics indicate merger-related cold gas in many WRGs, particularly XRGs, which also more frequently host powerful AGN, while ZRGs are more often classified as low-excitation radio galaxies (LERGs). This is consistent with our previous results showing that, although most WRGs exhibit FR II morphologies, FR I sources are almost exclusively ZRGs, suggesting that Z-shaped structures are statistically associated with lower jet power and are therefore more susceptible to perturbations. Nevertheless, the physical processes responsible for shaping XRGs and ZRGs need not be fundamentally different. Instead, the final morphology likely reflects the interplay between jet power, jet stability, and the surrounding environment.