Buoyant radio lobes in a viscous intracluster medium

By C. Reynolds, B. McKernan, A. C. Fabian, James M. Stone, John C. Vernaleo. 2004

140 citations recorded by the source corpus.

Ideal hydrodynamic models of the intracluster medium (ICM) in the core regions of galaxy clusters fail to explain both the observed temperature structure of this gas, and the observed morphology of radio-galaxy/ICM interactions. It has recently been suggested that, even in the presence of reasonable magnetic fields, thermal conduction in the ICM may be crucial for reproducing the temperature floor seen in many systems. If this is indeed correct, it raises the possibility that other transport processes may be important. With this motivation, we present a numerical investigation of the buoyant evolution of AGN-blown cavities in ICM that has a nonnegligible shear viscosity. We use the ZEUS-MP code to follow the three-dimensional evolution of an initially static, hot bubble in a β-model ICM atmosphere with varying degrees of shear viscosity. With no explicit viscosity, it is found that the combined action of Rayleigh‐Taylor and Kelvin‐Helmholtz instabilities rapidly shred the ICM cavity and one does not reproduce the intact and detached ‘ghost cavities’ observed in systems such as Perseus-A. On the other hand, even a modest level of shear viscosity (corresponding to approximately 25 per cent of the Spitzer value) can be important in quenching the fluid instabilities and maintaining the integrity of the bubble. In particular, we show that the morphology of the north-west ghost cavity found in Perseus-A can be reproduced, as can the flow pattern inferred from the morphology of Hα filaments. Finally, we discuss the possible relevance of ICM viscosity to the fact that many of the active ICM cavities (i.e. those currently associated with active radio lobes) are not bounded by strong shocks, the so-called ‘shock problem’. Ke yw ords: hydrodynamics ‐ cooling flows ‐ galaxies: jets ‐ X-rays: galaxies: clusters.

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Citations in the corpus

Hydrodynamical simulations of cluster formation with central AGN heating (2005, background): “Recently, the first mesh-based studies of isolated clusters with viscosity and bubble heating have appeared (e.g. Ruszkowski, Brüggen & Begelman 2004; Reynolds et al. 2005; Brüggen, Ruszkowski & Hallman 2005).”
On the treatment of entropy mixing in numerical cosmology (2008, background): “…been investigated by other authors, with particular emphasis on the evolution of hot bubbles generated by active galactic nuclei (AGN) and the impact of differing levels of conduction and viscosity due to magnetic fields with both grid codes and SPH (Reynolds et al. 2005; Sijacki & Springel 2006).”
Improved constraints on dark energy from Chandra X-ray observations of the largest relaxed galaxy clusters (2007, background): “…Recent work on the morphologies of X-ray cavities and Hα filaments suggest a relatively high gas viscosity (low Reynolds number) in nearby cluster cores (Fabian et al. 2003a,b,2005, Ruszkowski, Brüggen & Begelman 2004, Reynolds et al. 2005). between the systematic allowances and model parameters.)”
ON THE ORIGIN OF THE EXTENDED Hα FILAMENTS IN COOLING FLOW CLUSTERS (2010, background): “In an effort to explain how an AGN can deposit energy into the ICM and quench cooling, much work has been focused on the evolution of bubbles blown in the ICM by radio jets (e.g., Churazov et al. 2001; Reynolds et al. 2005; Vernaleo & Reynolds 2007; Revaz et al. 2008).”
THE FERMI BUBBLES. I. POSSIBLE EVIDENCE FOR RECENT AGN JET ACTIVITY IN THE GALAXY (2011, background): “…surface instabilities have received much attention in numerical studies of radio bubbles and X-ray cavities in galaxy clusters, where gas viscosity (Reynolds et al. 2005) and magnetic tension (Ruszkowski et al. 2007), have been invoked to successfully suppress these instabilities at the boundaries…”
Feedback heating by cosmic rays in clusters of galaxies (2007, methodology): “…show that the surfaces of buoyant bubbles are highly susceptible to disruption by Rayleigh-Taylor and Kelvin-Helmholz instabilities (e.g. Brüggen & Kaiser 2002), unless viscosity or magnetic fields are invoked to suppress these instabilities (e.g. Reynolds et al. 2005; Ruszkowski et al. 2007).”
On the prevalence of radio‐loud active galactic nuclei in brightest cluster galaxies: implications for AGN heating of cooling flows (2006, background): “Further, Reynolds et al. (2005) argue that viscosity at about 25 per cent of the Spitzer value will make the radio bubbles in the intracluster medium stable against Rayleigh–Taylor and Kelvin–Helmholtz instabilities (although magnetic fields offer another possibility for providing this required…”
AGN Feedback and Cooling Flows: Problems with Simple Hydrodynamic Models (2005, methodology): “…& Alexander 2003; Omma et al. 2004; Omma & Binney 2004; Dalla Vecchia et al. 2004; Robinson et al. 2004; Zanni et al. 2005), the effect of plasma transport processes (Ruszkowski et al. 2004; Reynolds et al. 2005b) and the action of magnetic fields (Robinson et al. 2004; Jones & De Young 2005).”