100-pc resolution of z~2 quasar host galaxies with ALMA: witnessing the formation of compact spheroids
With the advent of ALMA, the interstellar medium of high-redshift galaxies can be probed at remarkable resolution and sensitivity. We push the limits of ALMA even further by studying strongly lensed galaxies where we are able to probe structures of 10s–100s parsecs in scale. Using novel lens modelling techniques, we reconstruct the molecular interstellar medium (ISM) structure and kinematics of z~2 galaxies hosting luminous quasars, to give a new perspective on the physical processes that drive the formation and evolution of quiescent galaxies, from birth to quiescence. A key aspect in this study is how spheroids formed very high stellar densities and grew concurrently with their supermassive black holes. We find evidence the quasar host galaxies are observed in a stage during a rapid transformation into compact spheroids, where a high density of dynamically unstable gas leads to efficient star formation and black hole accretion. Furthermore, I present first results of mapping the structure and kinematics across the CO ladder – the highest resolution of the molecular ISM for a quasar host at cosmic noon – which demonstrates a highly non-homogeneous ISM.
