Chaotic cold accretion on to black holes
By M. Gaspari, M. Ruszkowski, S. Oh. 2013
318 citations recorded by the source corpus.
Using 3D AMR simulations, linking the 50 kpc to the sub-pc scales over the course of 40 Myr, we systematically relax the classic Bondi assumptions in a typical galaxy hosting a SMBH. In the realistic scenario, where the hot gas is cooling, while heated and stirred on large scales, the accretion rate is boosted up to two orders of magnitude compared with the Bondi prediction. The cause is the nonlinear growth of thermal instabilities, leading to the condensation of cold clouds and filaments when t_cool/t_ff 0.2) induces the formation of thermal instabilities, even in the absence of heating, while in the transonic regime turbulent dissipation inhibits their growth (t_turb/t_cool < 1). When heating restores global thermodynamic balance, the formation of the multiphase medium is violent, and the mode of accretion is fully cold and chaotic. The recurrent collisions and tidal forces between clouds, filaments and the central clumpy torus promote angular momentum cancellation, hence boosting accretion. On sub-pc scales the clouds are channelled to the very centre via a funnel. A good approximation to the accretion rate is the cooling rate, which can be used as subgrid model, physically reproducing the boost factor of 100 required by cosmological simulations, while accounting for fluctuations. Chaotic cold accretion may be common in many systems, such as hot galactic halos, groups, and clusters, generating high-velocity clouds and strong variations of the AGN luminosity and jet orientation. In this mode, the black hole can quickly react to the state of the entire host galaxy, leading to efficient self-regulated AGN feedback and the symbiotic Magorrian relation. During phases of overheating, the hot mode becomes the single channel of accretion (with a different cuspy temperature profile), though strongly suppressed by turbulence.
Subfields: Astronomy and Astrophysics, Global and Planetary Change
View Paper: https://www.semanticscholar.org/paper/c76a6fd1e1543340b3eaedf10f316766b5fd096e
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Citations in the corpus
- The multi-phase winds of Markarian 231: from the hot, nuclear, ultra-fast wind to the galaxy-scale, molecular outflow (2015, background): “Simulations of AGN feedback triggered by cold precipitation produce indeed a multi-phase structure of the gas in the galaxy cores (Gaspari et al. 2013).”
- Simulating galaxy formation with black hole driven thermal and kinetic feedback (2016, background): “First, the detailed physical mechanisms of both accretion on to SMBHs (Hopkins & Quataert 2010, 2011; Anglés-Alcázar et al. 2013; Gaspari et al. 2013; Anglés-Alcázar et al. 2015, 2016; Curtis & Sijacki 2015, 2016; Emsellem et al. 2015; Rosas-Guevara et al. 2015) and the AGN-gas interaction…”
- The Coevolution of Galaxies and Supermassive Black Holes: Insights from Surveys of the Contemporary Universe (2014, background): “Hydrodynamic simulations (most recently by Gaspari et al. 2013) including gas cooling, turbulence and feedback from AGN heating, reveal that when the hot gas is cooling then accretion on to the black hole occurs predominantly in a cold and chaotic manner.”
- A Global Model for Circumgalactic and Cluster-core Precipitation (2016, methodology): “Taken together, the simulations of Sharma et al. (2012b) and Gaspari et al. (2013) have been viewed as support for the suggestion that systems in global thermal balance naturally stabilize near min(tcool/tff) ≈ 10, as observed in more realistic simulations of cluster cores regulated by…”
- Hot Accretion Flows Around Black Holes (2014, result): “This could potentially boost the accretion rate by up to two orders of magnitude compared to the Bondi rate calculated based purely on hot gas (Gaspari et al. 2013).”
- AGN wind scaling relations and the co-evolution of black holes and galaxies (2017, background): “Thus, a multiphase gas structure naturally develops in cluster cores and within the BCGs leading to AGN feedback triggered by cold accretion (Gaspari et al. 2012, 2013, 2014, 2017).”