Winds of Quench: Multi-facility Constraints on AGN-driven Quenching at z > 3

High-z massive quenched galaxies (MQGs) form and quench very quickly, challenging theoretical models. AGN feedback is thought to play a central role, but the dominant mechanism remains elusive. We present deep JWST/NIRSpec IFU observations of two MQGs caught at different stages of quenching. GS-9209 (z=4.7) is already quenched yet hosts a residual neutral gas outflow, while GS-10578 (z=3.1) is observed transitioning to quiescence during an intense AGN-driven outflow episode. Our IFU study enables a robust characterisation of the geometry and spatial extent of outflowing gas. Together with the observation of older stellar cores in these galaxies, we show that AGN ejective feedback is strongly linked to inside-out quenching. We also present 9 MQGs at z=2-5 observed in ALMA Cycle 11; all are depleted of cold gas (<5% cold gas mass fraction; 5 sigma). Reconstructed gas-consumption histories indicate very short depletion timescales and reveal a diversity of quenching pathways, with some galaxies requiring gas removal while others are consistent with rapid gas consumption. However, JWST spectroscopy reveals that, in targets with neutral gas outflows, the gas cannot escape the galaxy's gravity, hence the need for preventative feedback to explain long-term quiescence. Finally, we discuss the implications of an approved ACA pilot program targeting the CGM of GS-10578 to search for expelled cold gas and a thermal Sunyaev–Zel'dovich signal, providing a test of AGN feedback at high-z.