Speaker
Description
Recent JWST observations revealed a surprising number of massive quiescent galaxies (MQGs) at $z>3$. These systems formed and quenched extremely rapidly within the first billion years, which provides new constraints on how ejective AGN feedback can expel large amounts of cold gas from early galaxies.
We will present ultra-deep, spatially resolved JWST/NIRSpec IFU spectroscopy observations of GS-9209 at z=4.66, one of the earliest known MQGs. This galaxy hosts a dormant supermassive black hole (SMBH) and a ring of hot dust, likely due to past SMBH driven outflows.
However, this galaxy shows an ordered stellar rotation pattern, indicating a dynamically gentle quenching mechanism. The $\left(V/\sigma\right)_{R_{e}}=0.8 \pm 0.26$ ratio (smaller than typical high redshift star-forming discs) proves that ejective AGN feedback is likely responsible for the short quenching timescale of this galaxy. Powerful neutral gas outflows (with $\eta>10$, detected in NaD and Ca II H absorption) deplete the cold gas reservoir of this galaxy, maintaining it quenched. The high spin parametre $\lambda_{R_{e}} =0.66 \pm 0.10$ suggests that the AGN-driven quenching does not require an immediate change in the morphology and kinematics of early galaxies. The galaxy shows an infant central bulge, but its B/T ratio is smaller than the prediction of SHARK semi-analytical models. This further reflects a lack of major mergers in galaxy's history.
Using Jeans Anisotropic Modelling we constrain the dark-matter fraction of this galaxy, showing that it is heavily dominated by baryons, and we discuss our findings in the context of similar systems observed by JWST at lower redshift.
