Radio and X-ray detectability of buoyant radio plasma bubbles  in
clusters of galaxies

Enßlin, T. A.; Heinz, Sebastian

doi:10.1051/0004-6361:20020207

Cited by 49 publications

(68 citation statements)

References 17 publications

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“…430 km s −1 . This is comparable to velocities of buoyant radio plasma bubbles (Enßlin & Heinz 2002), which are expected to stir up turbulence (e.g. Churazov et al 2001).…”

Section: Observationsmentioning

confidence: 75%

Magnetic turbulence in cool cores of galaxy clusters

Enßlin

Vogt

2006

A&A

Self Cite

103

107

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We argue that the recently reported Kolmogorov-like magnetic turbulence spectrum in the cool core of the Hydra A galaxy cluster can be understood by kinetic energy injection by active galaxies that drives a turbulent non-helical magnetic dynamo into its saturated state. Although dramatic differences exist between small-scale dynamo scenarios, their saturated state is expected to be similar, as we show for three scenarios: the flux rope dynamo, the fluctuation dynamo, and the explosive dynamo. Based on those scenarios, we develop an analytical model of the hydrodynamic and magnetic turbulence in cool cores. The model implies magnetic field strengths that fit well with Faraday rotation measurements and minimum energy estimates for the sample of cool core clusters having such data available. Predictions for magnetic fields in clusters for which the appropriate observational information is still missing, and for yet unobserved quantities like the hydrodynamical turbulence velocity and characteristic length-scale are provided. The underlying dynamo models suggest magnetic intermittency and possibly a large-scale hydrodynamic viscosity. We conclude that the success of the model to explain the field strength in cool core clusters indicates that in general cluster magnetic fields directly reflect hydrodynamical turbulence, also in clusters without cool cores.

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“…430 km s −1 . This is comparable to velocities of buoyant radio plasma bubbles (Enßlin & Heinz 2002), which are expected to stir up turbulence (e.g. Churazov et al 2001).…”

Section: Observationsmentioning

confidence: 75%

Magnetic turbulence in cool cores of galaxy clusters

Enßlin

Vogt

2006

A&A

Self Cite

103

107

View full text Add to dashboard Cite

show abstract

“…This suggests that the dimensions of the bubbles are small. Ensslin & Heinz (2002) discussed the dynamics of the rise of buoyant light bubbles within the cluster atmosphere (see also Churazov et al 2001;Kaiser 2003). The buoyant bubble rapidly reaches a terminal velocity v b .…”

Section: Discussionmentioning

confidence: 99%

“…By equating equations (16) and (17) the velocity of the bubble can be determined. Ensslin & Heinz (2002) derived v b under the assumption that the density of the ICM is well described by an isothermal -model and the density contrast Á $ 1. In this case v b is a fraction [/(r b =r c ) 1=2 ; r c is the core radius of the cluster] of the sound velocity.…”

Section: Discussionmentioning

confidence: 99%

Radiative Cooling and Heating and Thermal Conduction in M87

Ghizzardi

Molendi

Pizzolato

et al. 2004

ApJ

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The crisis of the standard cooling flow model brought about by Chandra and XMM-Newton observations of galaxy clusters has led to the development of several models that explore different heating processes in order to assess whether they can quench the cooling flow. Among the most appealing mechanisms are thermal conduction and heating through buoyant gas deposited in the intracluster medium (ICM) by active galactic nuclei (AGNs). We combine Virgo/M87 observations of three satellites (Chandra, XMM-Newton, and BeppoSAX ) to inspect the dynamics of the ICM in the center of the cluster. Using the spectral deprojection technique, we derive the physical quantities describing the ICM and determine the extra heating needed to balance the cooling flow, assuming that thermal conduction operates at a fixed fraction of the Spitzer value. We assume that the extra heating is due to buoyant gas, and we fit the data using the model developed by Ruszkowski and Begelman. We derive a scale radius for the model of $5 kpc, which is comparable with the M87 AGN jet extension, and a required luminosity of the AGN of a few ; 10 42 ergs s À1 , which is comparable to the observed AGN luminosity. We discuss a scenario in which the buoyant bubbles are filled with relativistic particles and magnetic field, which are responsible for the radio emission in M87. The AGN is supposed to be intermittent and to inject populations of buoyant bubbles through a succession of outbursts. We also study the X-ray-cool component detected in the radio lobes and suggest that it is structured in blobs that are tied to the radio buoyant bubbles.

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“…430 km/s. This is comparable to velocities of buoyant radio plasma bubbles (Enßlin & Heinz 2002), which are expected to stir up turbulence (e. g. Churazov et al 2001). C. The expected turbulence injection scale in the Hydra A cluster core is of the order of λ T ∼ λ B R 1/2 c ∼ 10 .…”

Section: Observationsmentioning

confidence: 70%

Magnetic turbulence in cool cores of galaxy clusters

Vogt¹,

Enßlin²

2006

Astron Nachr

Self Cite

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Abstract. We argue that the recently reported Kolmogorov-like magnetic turbulence spectrum in the cool core of the Hydra A galaxy cluster can be understood by kinetic energy injection by active galaxies that drives a turbulent non-helical magnetic dynamo into its saturated state. Although dramatic differences exist between small-scale dynamo scenarios, their saturated state is expected to be similar, as we show for three scenarios: the ¤ux rope dynamo, the ¤uctuation dynamo, and the explosive dynamo. Based on those scenarios, we develop an analytical model of the hydrodynamic and magnetic turbulence in cool cores. The model implies magnetic £eld strengths that £t well with Faraday rotation measurements and minimum energy estimates for the sample of cool core clusters having such data available. Predictions for magnetic £elds in clusters for which the appropriate observational information is still missing, and for yet unobserved quantities like the hydrodynamical turbulence velocity and characteristic length-scale are provided. The underlying dynamo models suggest magnetic intermittency and possibly a largescale hydrodynamic viscosity. We conclude that the success of the model to explain the £eld strength in cool core clusters indicates that in general cluster magnetic £elds directly re¤ect hydrodynamical turbulence, also in clusters without cool cores.

show abstract

Radio and X-ray detectability of buoyant radio plasma bubbles in clusters of galaxies

Cited by 49 publications

References 17 publications

Magnetic turbulence in cool cores of galaxy clusters

Magnetic turbulence in cool cores of galaxy clusters

Radiative Cooling and Heating and Thermal Conduction in M87

Magnetic turbulence in cool cores of galaxy clusters

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