Abstract

Gaseous outflows are key phenomena in the evolution of galaxies, as they affect star formation (either positively or negatively), eject gas from the core or disk, and directly cause mixing of pristine and processed material. Active outflows may be detected through searches for low-level, broad spectral line emission, but it is also possible to determine the presence of past outflows by examining the current brightness distribution of galaxies. In this work, we examine the CO(3-2) emission of a set of z=2.0-2.5 AGN host galaxies (a subset of the SUPER sample), as observed with ALMA . By performing a three-dimensional stacking analysis, collapsing the resulting stacked cubes, and extracting radial brightness profiles, we find evidence for a gaseous halo of r=15kpc. This is verified by creating a model of one or two 2D Gaussian models, convolving them with the stacked PSF , and using the Bayesian inference code MultiNest to fit the Gaussian properties so that the extracted brightness profiles are matched. We extend this analysis to the HST /ACS i-band images of the SUPER sample, which show a complex small-scale (r lower than 5kpc) morphology but no evidence for an extended halo. Thus, the CO(3-2) data for the SUPER AG Ns represents one of the best cases of gaseous halos at cosmic noon.