Morphology of Rising Hydrodynamic and Magnetohydrodynamic Bubbles from Numerical Simulations

Robinson, K.; Dursi, L. J.; Ricker, P. M.; Rosner, R.; Calder, A. C.; Zingale, M.; Truran, J. W.; Linde, Timur; Caceres, A.; Fryxell, B.; Olson, K.; Riley, Katherine; Siegel, A.; Vladimirova, Natalia

doi:10.1086/380817

Cited by 96 publications

(102 citation statements)

References 44 publications

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“…First, our simulations include magnetic fields, while theirs are purely hydrodynamic. As a result, the AGN bubbles in our simulations in general keep their integrity for longer periods of time, reach to further distances, and mix with the ambient ICM more slowly, because of the suppression of hydrodynamic instabilities by magnetic tension at the surface of the bubbles (e.g., Robinson et al 2004). Because it is more difficult for the bubbles to couple with the ICM, in general a lower feedback efficiency ò (thus a smaller radius of influence and higher thermalization efficiency) needs to be used in the MHD simulations in order to generate similar profiles to thosein hydrodynamic simulations.…”

Section: Comparisons With Previous Workmentioning

confidence: 92%

Interplay Among Cooling, Agn Feedback, and Anisotropic Conduction in the Cool Cores of Galaxy Clusters

Yang

Reynolds

2016

ApJ

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Feedback from the active galactic nuclei (AGNs) is one of the most promising heating mechanisms to circumvent the cooling-flow problem in galaxy clusters. However, the role of thermal conduction remains unclear. Previous studies have shown that anisotropic thermal conduction in cluster cool cores (CCs) could drive the heat-flux-driven buoyancy instabilities (HBIs) that reorient the field lines in the azimuthal directions and isolate the cores from conductive heating from the outskirts. However, how the AGN interacts with the HBI is still unknown. To understand these interwined processes, we perform the first 3D magnetohydrodynamic simulations of isolated CC clusters that include anisotropic conduction, radiative cooling, and AGN feedback. We find the following: (1) For realistic magnetic field strengths in clusters, magnetic tension can suppress a significant portion of HBI-unstable modes, and thus the HBI is either completely inhibited or significantly impaired, depending on the unknown magnetic field coherence length. (2) Turbulence driven by AGN jets can effectively randomize magnetic field lines and sustain conductivity at ∼1/3 of the Spitzer value; however, the AGN-driven turbulence is not volumefilling. (3) Conductive heating within the cores could contribute to ∼10% of the radiative losses in Perseus-like clusters and up to ∼50% for clusters twice the mass of Perseus. (4) Thermal conduction has various impacts on the AGN activity and intracluster medium properties for the hottest clusters, which may be searched by future observations to constrain the level of conductivity in clusters. The distribution of cold gas and the implications are also discussed.

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Section: Comparisons With Previous Workmentioning

confidence: 92%

Interplay Among Cooling, Agn Feedback, and Anisotropic Conduction in the Cool Cores of Galaxy Clusters

Yang

Reynolds

2016

ApJ

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“…Although in two dimensions magnetic fields act to stabilize some instabilities (e.g., Robinson et al 2004), in three dimensions the magnetic fields cannot suppress instabilities with wave-vector components perpendicular to the field lines. Hence, we do not expect magnetic fields to suppress mixing, but only to influence the details of the mixing.…”

Section: Numerical Setupmentioning

confidence: 99%

Heating the intracluster medium by jet-inflated bubbles

Hillel

Soker

2015

Mon. Not. R. Astron. Soc.

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We examine the heating of the intra-cluster medium (ICM) of cooling flow clusters of galaxies by jet-inflated bubbles and conclude that mixing of hot bubble gas with the ICM is more important than turbulent heating and shock heating. We use the pluto hydrodynamical code in full 3D to properly account for the inflation of the bubbles and to the multiple vortices induced by the jets and bubbles. The vortices mix some hot shocked jet gas with the ICM. For the parameters used by us the mixing process accounts for about four times as much heating as that by the kinetic energy in the ICM, namely, turbulence and sound waves. We conclude that turbulent heating plays a smaller role than mixing. Heating by shocks is even less efficient.

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“…While it has been common to conduct bubble stability studies beginning with static, pre-formed bubbles (e.g., Robinson et al 2004;Ruszkowski et al 2007), instead Jones & De Young (2005) gently "pressure inflated" their bubble structures over a period of at least 10 Myr during their simulations. Since real relic bubbles are not created instantaneously, they argued that relevant stability issues, including magnetic field geometries, may be sensitive to that fact.…”

Section: The Bubblesmentioning

confidence: 99%

“…Hydrodynamic simulations conducted by Kaiser (2001) in 2D andBrüggen et al (2002) in 3D confirmed the anticipated timescales of ∼ 10 7 years for disruption from hydrodynamical instabilities in such bubbles. To explore the effects of magnetic fields on bubble dynamics and stability, Robinson et al (2004) and Jones & De Young (2005) conducted multiple series of 2D magnetohydrodynamic (MHD) simulations involving relatively homogeneous ambient magnetic fields with a variety of field orientations with respect to the cluster gravitational field. Once again the bubble rise times were ∼ 10 8 years.…”

Section: Introductionmentioning

confidence: 99%

Three-Dimensional Magnetohydrodynamic Simulations of Buoyant Bubbles in Galaxy Clusters

O’Neill¹,

Young²,

Jones³

et al. 2009

AIP Conference Proceedings

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We report results of 3D MHD simulations of the dynamics of buoyant bubbles in magnetized galaxy cluster media. The simulations are three dimensional extensions of two dimensional calculations reported by Jones & De Young (2005). Initially spherical bubbles and briefly inflated spherical bubbles all with radii a few times smaller than the intracluster medium (ICM) scale height were followed as they rose through several ICM scale heights. Such bubbles quickly evolve into a toroidal form that, in the absence of magnetic influences, is stable against fragmentation in our simulations. This ring formation results from (commonly used) initial conditions that cause ICM material below the bubbles to drive upwards through the bubble, creating a vortex ring; that is, hydrostatic bubbles develop into "smoke rings", if they are initially not very much smaller or very much larger than the ICM scale height.Even modest ICM magnetic fields with β = P gas /P mag 10 3 can influence the dynamics of the bubbles, provided the fields are not tangled on scales comparable to or smaller than the size of the bubbles. Quasi-uniform, horizontal fields with initial β ∼ 10 2 bifurcated our bubbles before they rose more than about a scale height of the ICM, and substantially weaker fields produced clear distortions. These behaviors resulted from stretching and amplification of ICM fields trapped in irregularities along the top surface of the young bubbles. On the other hand, tangled magnetic fields with similar, modest strengths are generally less easily amplified by the bubble motions and are thus less influential in bubble evolution. Inclusion of a comparably strong, tangled magnetic field inside the initial bubbles had little effect on our bubble evolution, since those fields were quickly diminished through expansion of the bubble and reconnection of the initial field.

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Morphology of Rising Hydrodynamic and Magnetohydrodynamic Bubbles from Numerical Simulations

Cited by 96 publications

References 44 publications

Interplay Among Cooling, Agn Feedback, and Anisotropic Conduction in the Cool Cores of Galaxy Clusters

Interplay Among Cooling, Agn Feedback, and Anisotropic Conduction in the Cool Cores of Galaxy Clusters

Heating the intracluster medium by jet-inflated bubbles

Three-Dimensional Magnetohydrodynamic Simulations of Buoyant Bubbles in Galaxy Clusters

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