Simulations Show AGN Feedback Can Enhance Rather Than Suppress Star Formation in Dwarf Galaxies
Astronomers have conducted a spatially resolved analysis of stellar populations in the inner kiloparsec of three active galactic nuclei (AGN) host galaxies, finding evidence that gas inflows simultaneously trigger star formation and fuel supermassive black hole activity. The study used near-infrared spectroscopy and multiple stellar population synthesis models to reconstruct star formation histories in NGC 3884, 3C 293, and CGCG 012-070. The findings support a self-sustaining feeding-feedback cycle in which AGN activity and circumnuclear star formation are closely linked rather than mutually exclusive.
A new study accepted for publication in The Astrophysical Journal presents spatially resolved stellar population analyses of three nearby AGN host galaxies — NGC 3884, 3C 293, and CGCG 012-070 — using near-infrared spectroscopy. While the stellar light in all three galaxies is dominated by intermediate-age to old populations (≥1 Gyr) with super-solar metallicities, all three stellar population synthesis models employed (M13, XSL, and FSPS) consistently detect recent star formation, or 'rejuvenation,' particularly in the nuclear regions. In NGC 3884 and 3C 293, stars aged between 0.2 and 0.7 Gyr form a ring-like structure around the nucleus, suggesting episodic circumnuclear star formation. A central drop in stellar metallicity across all galaxies is interpreted as evidence of metal-poor gas inflows that fuel both recent star formation and AGN accretion. Non-stellar components — including a featureless power-law continuum and hot dust emission — were required to fit the nuclear spectra, and in 3C 293, the power-law component appears in two spatially separated regions, raising the possibility of a dual AGN, though a heavily reddened starburst cannot be ruled out. The three models broadly agree on the coexistence of old and young stellar components, though FSPS favors a higher fraction of very young stars (under 50 Myr) and produces more irregular star formation histories than M13. Taken together, the results support a scenario in which gas inflows trigger circumnuclear star formation, and subsequent stellar mass loss helps sustain ongoing AGN activity in a continuous feeding-feedback loop.
What's missing
The sample size of three galaxies limits the generalizability of the feeding-feedback scenario to the broader AGN population.
What different sources said
- arXiv astro-phCenter
Blowing star formation away in AGN hosts (BAH) -- V: The Feeding-Feedback Cycle in local AGNs as reveled by their stellar populations
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