How to feed your dragon: the role of turbulence in AGN activity
Abstract
Active galactic nuclei (AGN) are thought to be important drivers of galaxy evolution. However, the way AGN jets couple their energy to the interstellar medium (ISM) remains poorly understood. Recent observations have revealed ∼kpc-scale jets in galaxies of different morphological types. Here, we use idealized turbulent box simulations with accreting black holes to investigate how jet-ISM interactions and feedback shape the evolution of jets. We show that a turbulent ISM is a key ingredient in both jet launching and jet propagation. Without turbulence, jet feedback initially shuts off the cold gas supply to the black hole and the system enters a steady state with jet power ≤ 1039 erg s−1 for a 106 M⊙ black hole. In a turbulent medium, jets fill voids with hot diffuse material which the turbulence then carries away, replenishing the black hole's fuel supply. However, above a critical jet efficiency factor, the jet begins to significantly deplete its fuel supply and enters a self-limiting accretion regime. This critical factor depends on the ISM Mach number, with lower turbulence yielding a lower threshold. Moreover, while the jet power depends on the ambient gas density in the vicinity of the black hole, we find that, at fixed turbulent structure, the morphology and extent of jet propagation are largely insensitive to the average background density; turbulence in the ISM dominates over mean density in setting how far jets propagate, although denser media experience higher total energy injection and stronger heating.
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BibTeX
@misc{borodina2026feed,
title = {{How to feed your dragon: the role of turbulence in AGN activity}},
author = {Olga Borodina and Jake S. Bennett and Yueying Ni and Rainer Weinberger and Michaela Hirschmann and Boon Kiat Oh and Lars Hernquist},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.40788},
eprint = {2610.40788},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.40788},
note = {CC BY-SA 4.0},
}
RIS
TY - UNPB
TI - How to feed your dragon: the role of turbulence in AGN activity
AU - Olga Borodina
AU - Jake S. Bennett
AU - Yueying Ni
AU - Rainer Weinberger
AU - Michaela Hirschmann
AU - Boon Kiat Oh
AU - Lars Hernquist
PY - 2026
DA - 2026/10/29
PB - arXiv
DO - 10.48550/arxiv.2610.40788
UR - https://arxiv.org/abs/2610.40788
AB - Active galactic nuclei (AGN) are thought to be important drivers of galaxy evolution. However, the way AGN jets couple their energy to the interstellar medium (ISM) remains poorly understood. Recent observations have revealed ∼kpc-scale jets in galaxies of different morphological types. Here, we use idealized turbulent box simulations with accreting black holes to investigate how jet-ISM interactions and feedback shape the evolution of jets. We show that a turbulent ISM is a key ingredient in both jet launching and jet propagation. Without turbulence, jet feedback initially shuts off the cold gas supply to the black hole and the system enters a steady state with jet power ≤ 10^39 erg s^−1 for a 10^6 M_⊙ black hole. In a turbulent medium, jets fill voids with hot diffuse material which the turbulence then carries away, replenishing the black hole's fuel supply. However, above a critical jet efficiency factor, the jet begins to significantly deplete its fuel supply and enters a self-limiting accretion regime. This critical factor depends on the ISM Mach number, with lower turbulence yielding a lower threshold. Moreover, while the jet power depends on the ambient gas density in the vicinity of the black hole, we find that, at fixed turbulent structure, the morphology and extent of jet propagation are largely insensitive to the average background density; turbulence in the ISM dominates over mean density in setting how far jets propagate, although denser media experience higher total energy injection and stronger heating.
ER -