Dr. Namrata Roy

A key question in galaxy evolution is understanding how galaxies completely stop (or “quench”) their star formation towards the end of their lifetime. Active galactic nuclei (AGN) driven feedback has been proposed to be a very efficient way to suppress star formation - but direct evidence of such feedback in typical quiescent galaxies has been restricted to only a handful of sources. In this talk, I will present evidence from a series of papers that a new (and relatively common) class of early-type galaxies, known as ‘red geysers’, may represent AGN “maintenance-mode” feedback in action. I will show that these galaxies, selected from SDSS IV - MaNGA survey, preferentially host low luminosity radio mode AGNs. Radio data shows a wide variety of interesting radio morphologies, including large radio lobes that extend tens of kpc outside the galaxy. Using optical spectroscopic data, I will present kinematic evidence of large-scale ionized winds driven out from the center of red geysers. Finally, these galaxies also show a significant amount of inflowing cool neutral gas in the interstellar medium, which might play a role in fueling the central AGN. The geysers show very little star formation despite abundant gas supply, thereby supporting a feedback picture. I will present our current estimates on the population-averaged feedback energy that the red geysers can supply and how that compares to requirements from current galaxy formation models.