Title: AGN Feedback Through Multiple Jet Cycles in the Seyfert Galaxy NGC 2639 Show Chinese title

Title: 塞弗特星系NGC 2639中通过多次喷流循环的活动星系核反馈

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. Show Chinese abstract

Abstract: 塞弗特星系 NGC 2639 曾被发现表现出三次活动星系核喷流/茧体活跃事件。我们在此展示了升级后的巨型米波射电望远镜（uGMRT）在 735 MHz 波段下拍摄的 NGC 2639 图像，该图像揭示了第四个活跃事件，这一发现通过观测到的与之前已知的通过卡尔·詹斯基大阵列（VLA）和甚长基线阵列（VLBA）探测到的 $\sim9$ 千秒差距射电源相互错位的射电茧体（大小为 $\sim1.5$ 千秒差距、$\sim360$ 秒差距以及 $\sim3$ 秒差距的喷流特征）得以见证。 利用谱变老软件BRATS，我们得出$\sim9$kpc、$\sim1.5$kpc和$\sim360$pc事件的年龄分别为$34^{+4}_{-6}$Myr、$11.8^{+1.7}_{-1.4}$Myr和$2.8^{+0.7}_{-0.5}$Myr，并得出结论小合并发生在$9-22$Myr之间。 NGC 2639 的中心$\sim6$千秒差距区域内显示出分子气体的短缺。GALEX NUV 图像还显示该区域近期恒星形成活动不足，而 NGC 2639 的恒星形成率（SFR）面密度比星系整体施密特定律低$5-18$倍。 这使得 NGC 2639 成为一种罕见的情况，即一个表现出间歇性喷流活动以及可能由喷流驱动的活动星系核反馈迹象的 Seyfert 星系。