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 + 27 more
TLDR
This paper identifies two distinct populations of AGN host galaxies transitioning between star formation and quiescence, suggesting AGN activity drives star formation.
Key contributions
- Identified two distinct AGN host galaxy populations ("bridge" and "branch") using JWST/NIRCam imaging.
- 'Bridge' galaxies are early-type with weaker point sources, transitioning between moderate and low star formation rates.
- 'Branch' galaxies are late-type with dominant AGN, showing star formation positively correlated with AGN fraction.
- Found AGN activity, not stellar mass or redshift, primarily determines star formation in these host galaxies.
Why it matters
This research provides crucial insights into how Active Galactic Nuclei (AGN) influence star formation in their host galaxies. By distinguishing two populations, it challenges previous assumptions about the primary drivers of star formation, highlighting the direct role of AGN activity.
Original 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.
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