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

TL;DR

This study uses multi-instrument imaging to decompose AGN host galaxies, revealing two distinct populations with different star formation behaviors, indicating AGN activity influences star formation more than stellar mass.

Contribution

It identifies two separate AGN host populations with different star formation properties and demonstrates their transition between star formation and quiescence using detailed imaging and SED modeling.

Findings

Two distinct AGN host populations identified: 'bridge' and 'branch'.

Both groups show evidence of recent transition between star formation and quiescence.

Star formation in AGN hosts is more influenced by AGN activity than stellar mass.

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 $\Delta \rm SFMS = -1$ 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.