Which AGN jets quench star formation in massive galaxies?

Kung Yi Su*, Philip F. Hopkins, Greg L. Bryan, Rachel S. Somerville, Christopher C. Hayward, Daniel Anglés-Alcázar, Claude André Faucher-Giguère, Sarah Wellons, Jonathan Stern, Bryan A. Terrazas, T. K. Chan, Matthew E. Orr, Cameron Hummels, Robert Feldmann, Dušan Kereš

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

32 Scopus citations


Without additional heating, radiative cooling of the halo gas of massive galaxies (Milky Way-mass and above) produces cold gas or stars exceeding that observed. Heating from active galactic nucleus (AGN) jets is likely required, but the jet properties remain unclear. This is particularly challenging for galaxy simulations, where the resolution is orders-of-magnitude insufficient to resolve jet formation and evolution. On such scales, the uncertain parameters include the jet energy form [kinetic, thermal, cosmic ray (CR)]; energy, momentum, and mass flux; magnetic fields; opening angle; precession; and duty cycle. We investigate these parameters in a 1014, M⊙ halo using high-resolution non-cosmological magnetohydrodynamic simulations with the FIRE-2 (Feedback In Realistic Environments) stellar feedback model, conduction, and viscosity. We explore which scenarios qualitatively meet observational constraints on the halo gas and show that CR-dominated jets most efficiently quench the galaxy by providing CR pressure support and modifying the thermal instability. Mildly relativistic (∼MeV or ∼1010K) thermal plasma jets work but require ∼10 times larger energy input. For fixed energy flux, jets with higher specific energy (longer cooling times) quench more effectively. For this halo mass, kinetic jets are inefficient at quenching unless they have wide opening or precession angles. Magnetic fields also matter less except when the magnetic energy flux reaches ≳ 1044 erg s-1 in a kinetic jet model, which significantly widens the jet cocoon. The criteria for a successful jet model are an optimal energy flux and a sufficiently wide jet cocoon with a long enough cooling time at the cooling radius.

Original languageEnglish
Pages (from-to)175-204
Number of pages30
JournalMonthly Notices of the Royal Astronomical Society
Issue number1
StatePublished - 1 Oct 2021


FundersFunder number
Caltech cluster
Flatiron InstituteAST-1715216, 17-ATP17-0067, AST-2009687, AST-1652522
XSEDETG-AST130039, TG-AST120025
National Science Foundation1715847, 1455342
National Aeronautics and Space Administration17-ATP17-0214, JPL 1589742, OAC-1835509, AST-1615955, AST-2006176, NNX15AT06G
Alfred P. Sloan Foundation
Simons Foundation
Research Corporation for Science Advancement
Science and Technology Facilities CouncilST/T000244/1
Schweizerischer Nationalfonds zur Förderung der Wissenschaftlichen Forschung194814, AST-1715101


    • cosmic rays
    • galaxies: clusters: intracluster medium
    • galaxies: jets
    • galaxies: magnetic fields
    • methods: numerical
    • turbulence


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