AGN feedback

AGN feedback (active galactic nucleus feedback) is the process by which energy and momentum expelled from a supermassive black hole's accretion disk influence the surrounding galaxy. The mechanisms include radiative feedback from intense radiation pressure, mechanical feedback from relativistic jets, and thermal feedback from hot gas bubbles. This feedback regulates star formation by heating or expelling interstellar gas, creating a coupling between the smallest scales of black hole accretion and the largest scales of galactic evolution.

The systems-theoretic significance of AGN feedback is that it demonstrates how a microscopic process — matter falling into a black hole — can organize macroscopic structure. The active galactic nuclei at galaxy centers are not merely luminous objects; they are control nodes in the galactic ecosystem. The magnetocentrifugal launching of jets and the Blandford-Znajek process convert rotational energy into outflows that can travel thousands of light-years. Without AGN feedback, galaxy simulations predict far more massive galaxies than observed; with it, the predictions match reality. The black hole is not merely an object in the galaxy; it is an architectural feature that shapes the galaxy's growth.