Affiliation: University of Nottingham

Contribution: Oral

Title: Investigating AGN activity in recently quenched galaxies at cosmic noon

Abstract: We still do not understand the processes responsible for quenching star formation in massive galaxies. AGN feedback is favoured by theoretical models, but so far direct observational evidence is limited. To tackle this problem, I will present a new analysis of AGN activity in a large sample of over 500 recently quenched (post-starburst) galaxies at cosmic noon (1<z<3), identified from deep infrared surveys in the UDS and COSMOS fields. Using deep Chandra X-ray observations we find no evidence for an excess of AGN activity in the recently quenched population compared to older passive galaxies. Instead, our findings are consistent with AGN being a stochastic phenomenon that traces the star-formation rate but does not appear to linger significantly into the post-starburst phase. Nevertheless, spectroscopy with JWST NIRSpec has revealed high-velocity outflows of neutral gas in a large fraction of our recently quenched galaxies, in many cases long after the star formation has ended. I will present an evolutionary scenario to reconcile these apparently contradictory observations, folding in additional clues provided by the large-scale clustering of these galaxies.

This contribution can be found here (pdf).