AGN Feedback and Cooling Flows: Problems with Simple Hydrodynamic Models

By John C. Vernaleo, C. Reynolds. 2005

158 citations recorded by the source corpus.

In recent years it has become increasingly clear that active galactic nuclei, and radio galaxies in particular, have an impact on large-scale structure and galaxy formation. In principle, radio galaxies are energetic enough to halt the cooling of the virialized intracluster medium (ICM) in the inner regions of galaxy clusters, solving the cooling flow problem and explaining the high-mass truncation of the galaxy luminosity function. We explore this process through a series of high-resolution, three-dimensional hydrodynamic simulations of jetted active galaxies that act in response to cooling-mediated accretion of an ICM atmosphere. We find that our models are incapable of producing a long-term balance of heating and cooling; catastrophic cooling can be delayed by the jet action but inevitably takes hold. At the heart of the failure of these models is the formation of a low-density channel through which the jet can freely flow, carrying its energy out of the cooling core. It is possible that this failure is due to an oversimplified treatment of the fast jet (which may underestimate the "dentist drill" effect). However, it seems likely that additional complexity (large-angle jet precession or ICM turbulence) or additional physics (magnetohydrodynamic effects and plasma transport processes) is required to produce a spatial distribution of jet heating that can prevent catastrophic cooling. This work also underscores the importance of including jet dynamics in any feedback model, as opposed to the isotropically inflated bubble approach taken in some previous works.

Subfields: Astronomy and Astrophysics, Computational Mechanics

View Paper: https://www.semanticscholar.org/paper/c2c26a1205f5659708d67f901c126ef66c964383

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In Astronomy and Astrophysics

1. Y. Dubois
2. J. Devriendt
3. M. Volonteri
4. M. Gaspari
5. Romain Teyssier
6. A. Slyz
7. P. Temi
8. F. Brighenti

In Computational Mechanics

1. Y. Dubois
2. M. Gaspari
3. Romain Teyssier
4. M. Volonteri
5. F. Brighenti
6. J. Devriendt
7. A. Benson
8. P. Temi

Citations in the corpus

• Mechanical AGN feedback: controlling the thermodynamical evolution of elliptical galaxies (2012, methodology): “…under several circumstances, with or without AGN heating (see for instance the ‘galactic drip’ 6 We refer the reader to G11a and G11b for comparisons with different AGN feedback models in other types of environment, such as galaxy clusters (Vernaleo & Reynolds 2006; Cattaneo & Teyssier 2007).”
• Heating Hot Atmospheres with Active Galactic Nuclei (2007, background): “Vernaleo & Reynolds (2006) found that even a variable hydrodynamic jet flowing into a static atmosphere is incapable of tranferring a significant fraction of its energy to the atmopshere.”
• Jet-regulated cooling catastrophe (2010, background): “…2001; Quilis, Bower & Balogh 2001; Reynolds, Heinz & Begelman 2001; Basson & Alexander 2003; Omma et al. 2004; Ruszkowski, Brüggen & Begelman 2004b; Vernaleo & Reynolds 2006; Cattaneo & Teyssier 2007; Simionescu et al. 2009; Gaibler, Krause & Camenzind 2009; O’Neill & Jones 2010) or cosmological…”
• CAUSE AND EFFECT OF FEEDBACK: MULTIPHASE GAS IN CLUSTER CORES HEATED BY AGN JETS (2011, background): “Random motions, either due to AGN, multiphase gas, and cosmological turbulence, strongly help the deposition of the feedback energy in the cool core, in contrast to idealized symmetric atmospheres (e.g., Vernaleo & Reynolds 2006).”
• Galaxy formation theory (2010, background): “…inflate bubbles which heat the intracluster medium (ICM) viaPdV work; Roychowdhury et al. 2004; Vecchia et al. 2004; Ruszkowski et al. 2008, but see Vernaleo and Reynolds 2006) to heating by outflows drivenby super-Eddington accretion (King 2009) and viscous dissipation of sound waves (Ruszkowski…”
• Formation of supermassive black holes (2010, background): “…cosmic times) will trigger the formation of collimated outflows (e.g. blazars) that do not cause feedback directly on the host (which is pierced through), but will deposit their kinetic energy at large distances, leaving the host unscathed (in a different context, see Vernaleo and Reynolds, 2006).”