James Webb Space Telescope Feed Post

The Relation Between AGN and Host Galaxy Properties: I. Obscured AGN reside in disturbed hosts at 0 < z < 4

Examples of figure output from statmorph showing strongly asymmetric/disturbed (top, As > 0.2), mildly asymmetric/disturbed (middle, 0.1 < As < 0.2), and symmetric/undisturbed (bottom, As < 0.1). The galaxy image is shown along the left column, and along the right column, the binary detection mask (segmentation map) used to calculate the shape asymmetry (As) parameter utilized in this study. The measurement is performed within the circular aperture set by rmax, defined by Rodriguez-Gomez et al. (2019) as the distance between the point that minimizes the standard asymmetry (A) and the most distant pixel that belongs to the detection mask (which differs slightly from the rmax value originally defined in Pawlik et al. 2016, who introduce As). The elliptical Petrosian aperture, centered on the point in the galaxy image that minimizes A, is used to calculate the sky background level in the galaxy image that sets the brightness threshold for the binary detection mask. Abstract: The morphology of a galaxy is a manifestation of the complex interplay of physical processes occurring within and around it, and therefore offers indirect clues to its formation and evolution. We use both visual classification and computer vision to verify the suspected connection between galaxy merging activity - as evidenced by a close/merging galaxy pair, or tidal features surrounding an apparently singular system - and AGN activity. This study makes use of JADES JWST/NIRCam imagery, along with an unprecedentedly complete sample of AGN built using JWST/MIRI photometry in the same field. This 0.9-25 micron dataset enables constraints on the host galaxy morphologies of the broadest possible range of AGN beyond z~1, including heavily obscured examples missing from previous studies. We consider two AGN samples, one consisting of lightly to highly obscured X-ray-selected AGN (Lyu et al. 2022), and the other, presumed Compton-thick mid-infrared-bright/X-ray-faint AGN recently revealed by MIRI (Lyu et al. 2023). Both samples contain a significant fraction of host galaxies with disturbed morphologies at all redshifts sampled, and increasingly so towards higher redshift and AGN bolometric luminosity. The most obscured systems show the highest fraction of strongly disturbed host galaxies at 95±4%, followed by the moderately and unobscured/lightly obscured subsets at 78±6% and 63±6.5%, respectively. From this pattern of disturbances, we conclude that mergers are common amongst obscured AGN, and that the obscured AGN phase may mark a period of significant SMBH growth. This finding presents tension with the leading model on AGN fueling mechanisms (Hopkins et al. 2014) that needs reconciling.