Program: GN-2025A-Q-202

The episodic nature of Active Galactic Nuclei (AGN) is an important ingredient in galaxy evolution models, however, the processes that cause the AGN to switch on and off are still unclear. The clearest example of this episodic nature is observed in radio-AGN, called restarted and remnant radio-AGN. Recently, simulations and observations have also highlighted the role of recycled stellar mass, ejected during stellar evolution, in triggering an AGN. This mass, available in abundance in the elliptical hosts of radio-AGN, could solve the puzzle of why some AGN restart and others do not. We propose to perform the first near-infrared spectra study of restarted and remnant radio-AGN, to determine the amount of recycled stellar mass in the nuclear region of these galaxies. We also aim to investigate the proportions of different stellar populations beyond the nuclear region, to test whether the cumulative feedback of restarted AGN have suppressed the star formation in these galaxies. With this pilot project of four sources, we intend to perform a proof of concept study that would help lay the groundwork for more investigation into the role of recycled gas in triggering AGN.