2023MNRAS.524.1615R

The Seyfert galaxy NGC 2639 was known to exhibit three episodes of active galactic nuclei (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 ∼9 kpc radio lobes misaligned with the previously known ∼1.5 kpc, ∼360 pc, and ∼3 pc 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 ∼9 kpc, ∼1.5 kpc, and ∼360 pc episodes to be, respectively, $34^{+4}_{-6}$, $11.8^{+1.7}_{-1.4}$, 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 ∼6 kpc region. The GALEX NUV image also shows a deficiency of recent star formation in the same region, while the star formation rate 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.