Dynamical Friction and Cooling Flows in Galaxy Clusters

Kim, Woong-Tae; El-Zant, Amr; Kamionkowski, Marc

doi:10.1086/432976

Cited by 42 publications

(68 citation statements)

References 82 publications

(107 reference statements)

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“…We thus conclude that heating by galaxy motions alone cannot be the main solution to the cooling flow problem, although it can delay the catastrophic event significantly (e.g., BS90; Kim et al 2005).…”

Section: Discussionmentioning

confidence: 88%

“…(c) Averaged input rates of the kinetic energy due to a single galaxy as functions of its mass. orbits with velocity dispersion km s Ϫ1 , in which case j p 800 r the equilibrium galaxy number density is , where (Kim et al 2005). Under this distri-…”

Section: Model and Methodsmentioning

confidence: 98%

“…Using Monte Carlo approaches, El-Zant et al (2004) showed that dynamical friction of galaxies can be a distributed source of heat if the mass-to-light ratio of galaxies exceeds 10. Kim et al (2005) found that heating by dynamical friction reduces the growth rates of thermal instability. All these works suggest that the effects of galaxy motions on thermodynamic evolution of ICM are by no means negligible.…”

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confidence: 99%

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Heating and Turbulence Driving by Galaxy Motions in Galaxy Clusters

Kim

2007

ApJ

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Using three-dimensional hydrodynamic simulations, we investigate heating and turbulence driving in an intracluster medium (ICM) by orbital motions of galaxies in a galaxy cluster. We consider Ng member galaxies on isothermal and isotropic orbits through an ICM typical of rich clusters. An introduction of the galaxies immediately produces gravitational wakes, providing perturbations that can potentially grow via resonant interaction with the background gas. When Ng^{1/2}Mg_11 < 100, where Mg_11 is each galaxy mass in units of 10^{11} Msun, the perturbations are in the linear regime and the resonant excitation of gravity waves is efficient to generate kinetic energy in the ICM, resulting in the velocity dispersion sigma_v ~ 2.2 Ng^{1/2}Mg_11 km/s. When Ng^{1/2}Mg_11 > 100, on the other hand, nonlinear fluctuations of the background ICM destroy galaxy wakes and thus render resonant excitation weak or absent. In this case, the kinetic energy saturates at the level corresponding to sigma_v ~ 220 km/s. The angle-averaged velocity power spectra of turbulence driven in our models have slopes in the range of -3.7 to -4.3. With the nonlinear saturation of resonant excitation, none of the cooling models considered are able to halt cooling catastrophe, suggesting that the galaxy motions alone are unlikely to solve the cooling flow problem.Comment: 12 pages including 3 figures, To appear in ApJ

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Section: Discussionmentioning

confidence: 88%

Section: Model and Methodsmentioning

confidence: 98%

mentioning

confidence: 99%

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Heating and Turbulence Driving by Galaxy Motions in Galaxy Clusters

Kim

2007

ApJ

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“…Sijacki et al 2008), the heating induced by galaxy motions (e.g. Kim et al 2005), or thermal conduction (e.g. Zakamska & Narayan 2003), have been suggested.…”

Section: Agn Feedbackmentioning

confidence: 99%

Large-Scale Structure Formation: From the First Non-linear Objects to Massive Galaxy Clusters

2014

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The large-scale structure of the Universe formed from initially small perturbations in the cosmic density field, leading to galaxy clusters with up to 10 15 M at the present day. Here, we review the formation of structures in the Universe, considering the first primordial galaxies and the most massive galaxy clusters as extreme cases of structure formation where fundamental processes such as gravity, turbulence, cooling and feedback are particularly relevant. The first non-linear objects in the Universe formed in dark matter halos with 10 5 − 10 8 M at redshifts 10 − 30, leading to the first stars and massive black holes. At later stages, larger scales became non-linear, leading to the formation of galaxy clusters, the most massive objects in the Universe. We describe here their formation via gravitational processes, including the self-similar scaling relations, as well as the observed deviations from such self-similarity and the related non-gravitational physics (cooling, stellar feedback, AGN). While on intermediate cluster scales the self-similar model is in good agreement with the observations, deviations from such self-similarity are apparent in the core regions, where numerical simulations do not reproduce the current observational results. The latter indicates that the interaction of different feedback processes may not be correctly accounted for in current simulations. Both in the most massive clusters of galaxies as well as during the formation of the first objects in the Universe, turbulent structures and shock waves appear to be common, suggesting them to be ubiquitous in the non-linear regime.

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“…725 on circular-orbit perturbers provided V p t = 2R p , where R p is the orbital radius. While all the theoretical studies mentioned above consider low-mass perturbers and find various astrophysical applications (e.g., Narayan 2000;El-Zant et al 2004;Kim et al 2005;Kim 2007;Conroy & Ostriker 2008;Villaver & Livio 2009), there are some situations such as in orbital decay of SMBHs or companions in common-envelope binaries, where perturbers have masses so large that the induced density wakes are in the nonlinear regime. Using hydrodynamic simulations, Kim & Kim (2009, hereafter KK09) extended the work of Ostriker (1999) to study nonlinear DF force for a very massive perturber on a straight-line trajectory.…”

Section: Introductionmentioning

confidence: 99%

Nonlinear Dynamical Friction of a Circular-Orbit Perturber in a Gaseous Medium

Kim¹

2010

ApJ

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We use three-dimensional hydrodynamic simulations to investigate the nonlinear gravitational responses of gas to, and the resulting drag forces on, very massive perturbers moving in circular orbits. This work extends our previous studies that explored the cases of low-mass perturbers in circular orbits and massive perturbers on straight-line trajectories. The background medium is assumed to be non-rotating, adiabatic with index 5/3, and uniform with density ρ 0 and sound speed a 0 . We model the gravitating perturber using a Plummer sphere with mass M p and softening radius r s in a uniform circular motion at speed V p and orbital radius R p , and run various models with differing R ≡ r s /R p , M ≡ V p /a 0 , and B ≡ GM p /(a 2 0 R p ). A quasi-steady density wake of a supersonic model consists of a hydrostatic envelope surrounding the perturber, an upstream bow shock, and a trailing low-density region. The continuous change in the direction of the perturber motion reduces the detached shock distance compared to the linear-trajectory cases, while the orbit-averaged gravity of the perturber gathers the gas toward the center of the orbit, modifying the background preshock density to ρ 1 ≈ (1+0.46B 1.1 )ρ 0 depending weakly on M. For sufficiently massive perturbers, the presence of a hydrostatic envelope makes the drag force smaller than the prediction of the linear perturbation theory, resulting in1; the drag force for low-mass perturbers with η B < 0.1 agrees well with the linear prediction. The nonlinear drag force becomes independent of R as long as R < η B /2, which places an upper limit on the perturber size for accurate evaluation of the drag force in numerical simulations.

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Dynamical Friction and Cooling Flows in Galaxy Clusters

Cited by 42 publications

References 82 publications

Heating and Turbulence Driving by Galaxy Motions in Galaxy Clusters

Heating and Turbulence Driving by Galaxy Motions in Galaxy Clusters

Large-Scale Structure Formation: From the First Non-linear Objects to Massive Galaxy Clusters

Nonlinear Dynamical Friction of a Circular-Orbit Perturber in a Gaseous Medium

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