PEARLS: Two Distinct Populations of AGN Hosts Moving Between Star Formation and Quiescence

Gibson B. Bowling, Rafael Ortiz, S. P. Willner, Seth H. Cohen, Timothy Carleton, Rogier A. Windhorst, Rolf A. Jansen, Christopher N. A. Willmer, W. Peter Maksym, Anton M. Koekemoer, Madeline A. Marshall, Rosalia O'Brien, Payaswini Saikia, Massimo Ricotti, Jordan C. J. D'Silva, Dan Coe, Christopher J. Conselice, Jose M. Diego, Simon P. Driver, Brenda L. Frye, Norman A. Grogin, Rachel Honor, Jake Summers, Nor Pirzkal, Aaron Robotham, Russell E. Ryan, Brent M. Smith, Haojing Yan, Cheng Cheng, Liam Nolan, Heidi B. Hammel, Stefanie N. Milam

First listed 2026-05-01 | Last updated 2026-05-01

Abstract

We present the results of AGN--host-galaxy decomposition using JWST/NIRCam, HST/ACS, and HST/WFC3 imaging of the North Ecliptic Pole Time Domain Field (NEP-TDF). The light-profiles of 36 NIRCam-selected AGN candidates are modeled for measurement of their point sources, and point source-subtracted host-galaxy emission is used in SED modeling for star formation rate (SFR) estimation. Offsets from the canonical star-forming main sequence (SFMS) show that the host galaxies form two distinct groups distinguished by their star formation: a ``bridge'' between the moderate SFRs of radio sources and low SFRs of X-ray sources, and a cleanly-separated ``branch'' above $Δ\rm SFMS = -1$ whose SFR trends positively with AGN fraction. Branch galaxies include late-type galaxies with X-ray and radio detections and more dominant point sources that are most certainly AGN, while bridge galaxies have predominantly early-type morphologies with weaker point sources that may be due to compact stellar bulges. Both groups show evidence of recent transition between star formation and quiescence, but neither group shows preference for higher or lower stellar mass or redshift, suggesting that star formation in NIRCam-selected AGN-hosts is more strongly determined by AGN activity than by stellar mass.

Short digest

Using NIRCam+HST imaging of the NEP-TDF, the authors GALFIT-decompose 36 NIRCam-selected AGN candidates, subtract the nuclear PSF, and SED-fit host-only fluxes to place each galaxy relative to the SFMS. The hosts bifurcate into a bridge connecting radio-like moderate SFRs to the low-SFR X-ray locus (mostly early types with weak point sources) and a cleanly separated branch above ΔSFMS = −1 where SFR rises with AGN fraction (late types with X-ray/radio counterparts and stronger nuclei). Both groups show signs of recent movement between star-forming and quiescent states with no preference in stellar mass or redshift, implying current SFRs track AGN activity more than M*. A caveat is that some bridge “nuclei” may be compact stellar bulges rather than AGN.

Key figures to inspect

• Figure 1: Scan the redshift-ordered RGB cutouts to gauge the morphological split (early vs late types) and note X/R/X+R flags; this helps anticipate which objects populate the high-AGN-fraction branch versus the lower-SFR bridge.
• Figure 2: Inspect GALFIT data–model–residual panels for IDs 2, 62, and 40 across filters to see how well the central PSF is isolated; strong residual cores flag truly nucleus-dominated systems, while smooth residuals suggest compact bulges that could mimic weak AGN (key to the bridge caveat).
• Figure 3: For ID 27, compare point-source (gold) vs total (blue) magnitudes versus rest wavelength to identify where the nucleus dominates (NIRCam) and where the host takes over (UV/optical), validating the need for host-only SEDs in SFMS offsets.
• Figure 4: Read off CIGALE host SED components and best-fit parameters (log SFR, M*, attenuation, dust) across the sample; use these to visualize which galaxies sit above the ΔSFMS = −1 threshold (branch) versus below (bridge).