Fig.
2 Active galactic nucleus (AGN) jets can suppress
cooling flows (and therefore quench star formation) in massive
galaxies if the following three criteria are met.
1. Moderate jet energy flux Enough energy for cocoon
expansion to balance gas cooling, but not so much energy as to
exceed escape velocity at Rcool.
2. Long cooling time within jet cocoon Longer than
time to reach Rcool. Can be achieved by thermal or kinetic
jets with high specific energy or CR jets.
3. Wide jet cocoon Width of cocoon at Rcool is enough
to suppress the cooling flow over a wide solid angle. Can be
achieved by jets with a high non-kinetic component, very light
kinetic jets, or jets with initially wide angles.