Viscous Kelvin–Helmholtz instabilities in highly ionized plasmas
Elke Roediger,Elke Roediger,Elke Roediger,Ralph P. Kraft,Paul Nulsen,E. M. Churazov,William R. Forman,Marcus Brüggen,R. Kokotanekova,R. Kokotanekova,R. Kokotanekova +10 more
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In this article, the authors studied the effect of constant and temperature-dependent isotropic viscosity over the full range of possible values and showed that moderate viscosities slow down the growth of the KHI and reduce the height of the kHI rolls and their rolling up.Abstract:
Transport coefficients in highly ionized plasmas like the intracluster medium (ICM) are still ill-constrained. They influence various processes, among them the mixing at shear flow interfaces due to the Kelvin–Helmholtz instability (KHI). The observed structure of potential mixing layers can be used to infer the transport coefficients, but the data interpretation requires a detailed knowledge of the long-term evolution of the KHI under different conditions. Here we present the first systematic numerical study of the effect of constant and temperature-dependent isotropic viscosity over the full range of possible values. We show that moderate viscosities slow down the growth of the KHI and reduce the height of the KHI rolls and their rolling-up. Viscosities above a critical value suppress the KHI. The effect can be quantified in terms of the Reynolds number Re=Uλν, where U is the shear velocity, λ the perturbation length and ν the kinematic viscosity. We derive the critical Re for constant and temperature-dependent Spitzer-like viscosities, an empirical relation for the viscous KHI growth time as a function of Re and density contrast, and describe special behaviours for Spitzer-like viscosities and high density contrasts. Finally, we briefly discuss several astrophysical situations where the viscous KHI could play a role, i.e. sloshing cold fronts, gas stripping from galaxies, buoyant cavities, ICM turbulence and high-velocity clouds.read more
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The relation between gas density and velocity power spectra in galaxy clusters: High-resolution hydrodynamic simulations and the role of conduction
TL;DR: In this article, the velocity field and its intimate relation with the ICM thermodynamic perturbations were studied using high-resolution 3D plasma simulations, and it was shown that the variance of density perturbation is comparable to the 1D Mach number, M 1D ~ δρ /ρ.
Journal ArticleDOI
The stripping of a galaxy group diving into the massive cluster A2142
Dominique Eckert,Dominique Eckert,Silvano Molendi,Matt S. Owers,Massimo Gaspari,Tiziana Venturi,Lawrence Rudnick,Stefano Ettori,Stéphane Paltani,Fabio Gastaldello,Fabio Gastaldello,Mariachiara Rossetti,Mariachiara Rossetti +12 more
TL;DR: In this paper, an irregular X-ray substructure in the outskirts of the massive galaxy cluster Abell 2142 has been detected, and the authors interpret this structure as a galaxy group in the process of being accreted onto the main dark-matter halo.
Journal ArticleDOI
The SAMI Galaxy Survey: spatially resolving the environmental quenching of star formation in GAMA galaxies
Adam L. Schaefer,Adam L. Schaefer,Scott M. Croom,J. T. Allen,Sarah Brough,Sarah Brough,Anne M. Medling,I-Ting Ho,I-Ting Ho,Nicholas Scott,Samuel N. Richards,Samuel N. Richards,Michael Pracy,Madusha Gunawardhana,Peder Norberg,Mehmet Alpaslan,Amanda E. Bauer,Kenji Bekki,Jonathan Bland-Hawthorn,J. V. Bloom,Julia J. Bryant,Julia J. Bryant,Warrick J. Couch,Simon P. Driver,Simon P. Driver,L. M. R. Fogarty,Caroline Foster,Gregory Goldstein,Andrew W. Green,Andrew M. Hopkins,Iraklis S. Konstantopoulos,Jon Lawrence,Angel R. Lopez-Sanchez,Angel R. Lopez-Sanchez,Nuria P. F. Lorente,Matt S. Owers,Matt S. Owers,Rob Sharp,Sarah M. Sweet,Edward N. Taylor,J. van de Sande,C. J. Walcher,O. I. Wong,O. I. Wong +43 more
TL;DR: In this paper, the authors used data from the Sydney-AAO Multi-Object Integral Field Spectrograph (SAMI) Galaxy Survey and the Galaxy And Mass Assembly (GAMA) survey to investigate the spatially-resolved signatures of the environmental quenching of star formation in galaxies.
Journal ArticleDOI
The effect of anisotropic viscosity on cold fronts in galaxy clusters
TL;DR: In this article, high-resolution simulations of cold fronts arising from subsonic gas sloshing in cluster cores using the grid-based Athena MHD code were performed, comparing the effects of isotropic Spitzer and anisotropic Braginskii viscosity (expected in a magnetized plasma).
Journal ArticleDOI
The relation between gas density and velocity power spectra in galaxy clusters: high-resolution hydrodynamic simulations and the role of conduction
TL;DR: In this article, the authors study the statistics of the velocity field and its relation with the thermodynamic perturbations, using high-resolution 3D plasma simulations, and show that the normalization of the ICM spectrum (density, entropy, or pressure) is linearly tied to the level of large-scale motions, which excite both gravity and sound waves due to stratification.
References
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An Introduction to Fluid Dynamics. By G. K. Batchelor. Pp. 615. 75s. (Cambridge.)
TL;DR: In this paper, the Navier-Stokes equation is derived for an inviscid fluid, and a finite difference method is proposed to solve the Euler's equations for a fluid flow in 3D space.
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A Textbook Example of a Bow Shock in the Merging Galaxy Cluster 1E 0657–56
Maxim Markevitch,Anthony H. Gonzalez,Laurence P. David,Alexey Vikhlinin,S. S. Murray,William R. Forman,C. Jones,W. H. Tucker,W. H. Tucker +8 more
TL;DR: The Chandra image of the merging, hot galaxy cluster 1E 0657-56 reveals a bow shock propagating in front of a bullet-like gas cloud just exiting the disrupted cluster core as mentioned in this paper.
Journal ArticleDOI
A Textbook Example of a Bow Shock in the Merging Galaxy Cluster 1E0657-56
Maxim Markevitch,Anthony H. Gonzalez,L. P. David,Alexey Vikhlinin,S. S. Murray,William R. Forman,C. Jones,W. Tucker +7 more
TL;DR: In this paper, Chandra image of the merging, hot galaxy cluster 1E0657-56 reveals a bow shock propagating in front of a bullet-like gas cloud just exiting the disrupted cluster core.