AGN Feedback Through Multiple Jet Cycles in the Seyfert Galaxy NGC 2639

TL;DR

This study reveals multiple episodes of AGN jet activity in NGC 2639, with ages ranging from a few million to over thirty million years, indicating episodic feedback likely driven by minor mergers and affecting the galaxy's gas and star formation.

Contribution

First detailed multi-epoch radio imaging of NGC 2639 showing four jet episodes and their ages, highlighting episodic AGN feedback in a Seyfert galaxy.

Findings

Discovery of a fourth, older radio lobe episode at 9 kpc.

Ages of jet episodes range from 2.8 to 34 Myr.

Evidence of jet-driven feedback reducing central gas and star formation.

Abstract

The Seyfert galaxy NGC 2639 was known to exhibit three episodes of AGN jet/lobe activity. We present here the upgraded Giant Metrewave Radio Telescope (uGMRT) 735 MHz image of NGC 2639 showing a fourth episode as witnessed by the discovery of $\sim9$ kpc radio lobes misaligned with the previously known $\sim1.5$ kpc, $\sim360$ parsec, and $\sim3$ parsec jet features detected through the Karl G. Jansky Very Large Array (VLA) and the Very Long Baseline Array (VLBA), respectively. Using the spectral ageing software BRATS, we derive the ages of the $\sim9$ kpc, $\sim1.5$ kpc, and $\sim360$ parsec episodes to be, respectively, $34^{+4}_{-6}$ Myr, $11.8^{+1.7}_{-1.4}$ Myr, and $2.8^{+0.7}_{-0.5}$ Myr, and conclude that minor mergers occurred $9-22$ Myr apart. NGC 2639 shows a deficit of molecular gas in its central $\sim6$ kpc region. The GALEX NUV image also shows a deficiency of recent star-formation in the same region, while the star formation rate (SFR) surface density in NGC 2639 is lower by a factor of $5-18$ compared to the global Schmidt law of star-forming galaxies. This makes NGC 2639 a rare case of a Seyfert galaxy showing episodic jet activity and possible signatures of jet-driven AGN feedback.