What is AGN Feedback?
Active Galactic Nuclei (AGN) — the supermassive black holes at the centers of galaxies — don’t just passively sit there. They actively inject energy into their host galaxies and beyond, regulating star formation and shaping the circumgalactic medium (CGM).
Understanding how this feedback works is one of the central questions in galaxy formation theory.
The CROCODILE Simulation
Our CROCODILE project implements a top-heavy initial mass function (IMF) in regions of intense star formation driven by AGN feedback. The key finding: this approach successfully reproduces circumgalactic medium metallicity patterns that match observational data.
Standard IMF models tend to underpredict the metal enrichment observed in the CGM of massive galaxies. By allowing the IMF to become top-heavy in AGN-influenced regions, we get better agreement with observations.
What This Means
The thermal AGN feedback channel is more important than previously thought. It’s not just about mechanical jets — the thermal heating from AGN activity changes which stars form and how metals are distributed across cosmic scales.
This work was presented at the Japanese Astronomical Society Spring Meeting (March 2025) and at several international workshops.
Next Steps
We’re now extending the model to include both kinetic and thermal AGN feedback modes and comparing results across different cosmological simulation codes (SPH vs. mesh-based).
Stay tuned for updates!