JWST Catches a Strongly Gravitationally Lensed AGN In Transition from Type II to Type I

Michael K Florian, Michael D Gladders, Gourav Khullar, Keren Sharon, Aidan P Cloonan, Eirk Solhaug, Brian Welch, Matthew Bayliss, Hakon Dahle, Taylor A Hutchison, Jane R Rigby

First listed 2025-10-12 | Last updated 2025-10-12

Abstract

JWST has enabled the discovery of a statistical sample of obscured (type II) active galactic nuclei (AGN) at cosmic noon. Studies comparing those type II AGN with type I AGN at that epoch have reinforced the long-standing idea of an evolutionary link between those classes of objects. Mergers, the idea goes, disturb the morphologies and angular momentum of galaxies. The disruption of angular momentum allows material to be funneled toward galactic cores, sparking AGN activity and potentially also a burst of star-formation. That material enshrouds the galactic nucleus, leading to a type II AGN. Later, AGN feedback clears the circumnuclear dust, leading to a transition into a type I AGN, and also quenches star formation. If this is a common outcome, a class of intermediate objects should exist. Such objects would be somewhat disturbed and dusty and sit below the star-forming galaxy main sequence, and their star-formation histories would show an increase in star-formation at around the time of the suspected merger. We present new JWST observations of SDSSJ2222+2745, a strongly lensed AGN at z=2.801. The lensing magnification enables a detailed study of the host galaxy spanning the rest-ultraviolet through near infrared. JWST and HST photometry, morphological models, and models of the host's spectral energy distribution reveal that SDSSJ2222+2745 is actively transitioning from a type II to type I AGN. Catching a lensed AGN at this special evolutionary phase makes SDSSJ2222+2745 a unique laboratory to study the physical processes involved in the transition and their relationships to the AGN and the host galaxy at incredible spatial-resolution down to about 20pc at z=2.801.

Short digest

JWST NIRCam plus HST imaging and lens modeling of the six-image system SDSSJ2222+2745 (z=2.801) enable host–AGN decomposition at ≈20 pc scales, with GALFIT morphology and rest-UV–NIR photometry. The host shows only minor asymmetry and modest dust, sits below the star-forming main sequence, and is not fully quenched. SED fitting indicates a last uptick in star formation ~300 Myr ago, consistent with a recent merger that ignited the AGN. Together these point to an AGN actively transitioning from type II to type I, offering a rare snapshot of the evolutionary link at cosmic noon.

Key figures to inspect

• Fig. 1 (NIRCam RGB F444W/F150W/F115W): Inspect all six lensed images (A–F) and the deep F444W insets to see intrinsic clumpy substructure in the host and the magnification-driven resolution reaching ≈20 pc.
• Fig. 2 (images A, B, C with clumps marked): Use the cross-image persistence of the two arrowed clumps—visible even in lower-magnification image C—to confirm these are real, minor host asymmetries rather than differential magnification artifacts.
• Fig. 3 (image A: data/GALFIT/residuals across F115W, F150W, F444W): Check PSF–host separation quality and wavelength-dependent residuals to validate the decomposition and reveal off-nuclear clumps driving the small asymmetry.
• Fig. 4 (image B: data/GALFIT/residuals): Compare to Fig. 3 to test robustness across a different parity/magnification region; consistent residual features strengthen the intrinsic-clump interpretation and color gradients informing the SED fit.