BlackHoleWeather -- Spin-coupled chaotic cold accretion across the meso scale: Variability and kinematics

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Main Authors: Piana, Olmo, Gaspari, Massimo, Cammelli, Vieri, Barbani, Filippo, Brustio, Davide M., Stel, Giovanni, Olivares, Valeria, Danehkar, Ashkbiz, Temi, Pasquale, Serafinelli, Roberto, Salvestrini, Francesco, Maccagni, Filippo M., Tombesi, Francesco
Format: Preprint
Published: 2026
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author Piana, Olmo
Gaspari, Massimo
Cammelli, Vieri
Barbani, Filippo
Brustio, Davide M.
Stel, Giovanni
Olivares, Valeria
Danehkar, Ashkbiz
Temi, Pasquale
Serafinelli, Roberto
Salvestrini, Francesco
Maccagni, Filippo M.
Tombesi, Francesco
author_facet Piana, Olmo
Gaspari, Massimo
Cammelli, Vieri
Barbani, Filippo
Brustio, Davide M.
Stel, Giovanni
Olivares, Valeria
Danehkar, Ashkbiz
Temi, Pasquale
Serafinelli, Roberto
Salvestrini, Francesco
Maccagni, Filippo M.
Tombesi, Francesco
contents Supermassive black hole (SMBH) spin records the vector history of accretion. In chaotic cold accretion (CCA), this history is set by clouds and filaments whose torques can add coherently, cancel, or reverse before reaching the horizon-scale closure. We test whether halo stirring regulates SMBH spin by changing the radial continuity and torque coherence of the meso-scale accretion bridge. We focus on spin evolution, jet-axis reorientation, accretion variability, and CCA kinematics. We analyse four 3D hydrodynamical simulations in a 100-kpc box, reaching sub-pc resolution, including SMBH spin-coupled jet feedback. All runs use the Hybrid SMBH spin model validated in a companion paper. Two simulations maintain continuous driven solenoidal turbulence, while two matched controls let the same initial turbulent field decay. The main effect of persistent stirring is to disrupt mass and angular-momentum continuity across the meso-scale bridge. Although all runs develop comparable macro-scale inflow, in the driven-turbulence suite, gas struggles to reach pc scales, and the radial accretion rate drops by 2-3 orders of magnitude. Torque delivery in this case is fragmented and cancellation-dominated. The interrupted-turbulence suite, on the other hand, preserves a connected gas channel to the sink, while sustaining higher torque coherence. Driven runs therefore settle to slow effective jet-axis drift, whereas interrupted runs maintain reorientation rates higher by about two orders of magnitude and can briefly reach a few degrees during coherent retrograde episodes. The same split appears in power spectra and k-plots: connected rain enhances low-frequency accretion power and produces narrower, phase-ordered kinematics, while stirring steepens high-frequency damping and broadens the gas velocity loci for all phases.
format Preprint
id arxiv_https___arxiv_org_abs_2605_27508
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle BlackHoleWeather -- Spin-coupled chaotic cold accretion across the meso scale: Variability and kinematics
Piana, Olmo
Gaspari, Massimo
Cammelli, Vieri
Barbani, Filippo
Brustio, Davide M.
Stel, Giovanni
Olivares, Valeria
Danehkar, Ashkbiz
Temi, Pasquale
Serafinelli, Roberto
Salvestrini, Francesco
Maccagni, Filippo M.
Tombesi, Francesco
Astrophysics of Galaxies
High Energy Astrophysical Phenomena
Supermassive black hole (SMBH) spin records the vector history of accretion. In chaotic cold accretion (CCA), this history is set by clouds and filaments whose torques can add coherently, cancel, or reverse before reaching the horizon-scale closure. We test whether halo stirring regulates SMBH spin by changing the radial continuity and torque coherence of the meso-scale accretion bridge. We focus on spin evolution, jet-axis reorientation, accretion variability, and CCA kinematics. We analyse four 3D hydrodynamical simulations in a 100-kpc box, reaching sub-pc resolution, including SMBH spin-coupled jet feedback. All runs use the Hybrid SMBH spin model validated in a companion paper. Two simulations maintain continuous driven solenoidal turbulence, while two matched controls let the same initial turbulent field decay. The main effect of persistent stirring is to disrupt mass and angular-momentum continuity across the meso-scale bridge. Although all runs develop comparable macro-scale inflow, in the driven-turbulence suite, gas struggles to reach pc scales, and the radial accretion rate drops by 2-3 orders of magnitude. Torque delivery in this case is fragmented and cancellation-dominated. The interrupted-turbulence suite, on the other hand, preserves a connected gas channel to the sink, while sustaining higher torque coherence. Driven runs therefore settle to slow effective jet-axis drift, whereas interrupted runs maintain reorientation rates higher by about two orders of magnitude and can briefly reach a few degrees during coherent retrograde episodes. The same split appears in power spectra and k-plots: connected rain enhances low-frequency accretion power and produces narrower, phase-ordered kinematics, while stirring steepens high-frequency damping and broadens the gas velocity loci for all phases.
title BlackHoleWeather -- Spin-coupled chaotic cold accretion across the meso scale: Variability and kinematics
topic Astrophysics of Galaxies
High Energy Astrophysical Phenomena
url https://arxiv.org/abs/2605.27508