The peculiar WAT NGC 2329 with Seyfert/FR I-like radio lobes

TL;DR

This study reveals the complex radio morphology of NGC 2329, showing a rare combination of Seyfert-like inner lobes and FR I-like outer lobes, indicating a possible evolutionary transition in AGN activity.

Contribution

It provides a detailed multi-resolution radio analysis of NGC 2329, highlighting the coexistence of Seyfert and FR I features and suggesting a temporal evolution in AGN radio properties.

Findings

Outer lobes are approximately 45 Myr old.

Inner lobes are approximately 25 Myr old.

The AGN may have undergone a recent rejuvenation due to gas inflow.

Abstract

We report the complex radio properties of the radio galaxy NGC 2329 that resides in the centre of the galaxy cluster Abell 569. For this study, we have used archival data from the Very Large Array (VLA) at various resolutions and frequencies, as well as the Very Long Baseline Array (VLBA). While the wide-angle tailed (WAT) Fanaroff-Riley type I (FR I) radio morphology of the source has been discussed widely in the literature, the nature of the inner lobes has not been as widely discussed. In particular, we note that the inner lobes resemble the bubble-like radio structures observed in Seyfert galaxies. Polarization-sensitive data from the VLA clearly show magnetic field structures consistent with FR Is for the outer lobes and Seyferts for the inner lobes in NGC 2329. FR Is are classified as radio-loud (RL) active galactic nuclei (AGN) and Seyferts as radio-quiet (RQ) AGN, making this source unique. The VLBA shows a one-sided radio jet suggesting a relativistic pc-scale outflow, leading into the inner lobes. Electron lifetime estimates suggest that the outer FR I-like lobes are nearly twice as old ($\sim$45 Myr) as the inner Seyfert-like lobes ($\sim$25 Myr). Gas inflow in this merging cluster seems to have rejuvenated the AGN about $\sim$25 Myr ago, and may have caused a change in the accretion disc state. The complex composite radio morphology of NGC 2329 suggests that the RL/RQ dichotomy is a function of time in the lifecycle of an AGN.