Positive AGN Feedback Enhances Star Formation in Starburst Dwarf Galaxies

TL;DR

This study shows that in starburst dwarf galaxies, AGN feedback can actually boost star formation by creating compressed gas regions, challenging the traditional view that it suppresses star formation.

Contribution

The paper demonstrates through high-resolution simulations that AGN feedback can enhance star formation in dwarf galaxies, a novel insight into galaxy evolution mechanisms.

Findings

AGN feedback increases star formation rates by ~25%.

AGN-driven outflows create compressed, cooling gas regions.

Positive feedback depends on combined AGN and supernova activity.

Abstract

The role of active galactic nuclei (AGN) feedback in dwarf galaxies remains poorly understood, with conventional wisdom suggesting it primarily suppresses star formation. Using high-resolution MACER3D simulations that directly resolve the Bondi radius, we demonstrate that AGN feedback can significantly enhance rather than suppress star formation in starburst dwarf galaxies. Our simulations reveal that AGN feedback increases global star formation rates by approximately 25% when comparing our models with both AGN and supernova feedback to those with only supernova feedback. This enhancement occurs through AGN-driven outflows creating compressed gas regions where efficient cooling preserves the high density while quickly radiating away thermal energy, creating ideal conditions for star formation. This positive feedback mechanism operates in gas-rich starburst environments with efficient cooling and moderate AGN energy input that compresses gas without expelling it from the galaxy. Critically, it requires both AGN and supernova feedback working in concert: without SN feedback to regulate black hole activity, AGN outflows become too powerful and expel gas rather than compress it. Our results closely match observations of the starburst dwarf galaxy Henize 2-10, where similar shock-compressed regions of enhanced star formation have been observed. These findings challenge conventional understanding of AGN feedback and suggest that AGN may play a previously unrecognized role in accelerating star formation during active phases of dwarf galaxy evolution.