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Kelvin-Helmholtz instabilities at the sloshing cold fronts in the Virgo cluster as a measure for the effective ICM viscosity

Roediger, E.; P. Kraft, R.; R. Forman, W.; E. J. Nulsen, P.; Churazov, E.

Authors

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Dr Elke Roediger E.Roediger@hull.ac.uk
Senior Lecturer/ Director of Studies for Physics

R. P. Kraft

W. R. Forman

P. E. J. Nulsen

E. Churazov



Abstract

Sloshing cold fronts (CFs) arise from minor merger triggered gas sloshing. Their detailed structure depends on the properties of the intra-cluster medium (ICM): hydrodynamical simulations predict the CFs to be distorted by Kelvin-Helmholtz instabilities (KHIs), but aligned magnetic fields, viscosity, or thermal conduction can suppress the KHIs. Thus, observing the detailed structure of sloshing CFs can be used to constrain these ICM properties. Both smooth and distorted sloshing CFs have been observed, indicating that the KHI is suppressed in some clusters, but not in all. Consequently, we need to address at least some sloshing clusters individually before drawing general conclusions about the ICM properties. We present the first detailed attempt to constrain the ICM properties in a specific cluster from the structure of its sloshing CF. Proximity and brightness make the Virgo cluster an ideal target. We combine observations and Virgo-specific hydrodynamical sloshing simulations. Here we focus on a Spitzer-like temperature dependent viscosity as a mechanism to suppress the KHI, but discuss the alternative mechanisms in detail. We identify the CF at 90 kpc north and north-east of the Virgo center as the best location in the cluster to observe a possible KHI suppression. For viscosities $\gtrsim$ 10% of the Spitzer value KHIs at this CF are suppressed. We describe in detail the observable signatures at low and high viscosities, i.e. in the presence or absence of KHIs. We find indications for a low ICM viscosity in archival XMM-Newton data and demonstrate the detectability of the predicted features in deep Chandra observations.

Journal Article Type Article
Publication Date Jan 28, 2013
Print ISSN 0004-637X
Publisher American Astronomical Society
Peer Reviewed Peer Reviewed
Volume 764
Issue 1
Article Number 60
APA6 Citation Roediger, E., P. Kraft, R., R. Forman, W., E. J. Nulsen, P., & Churazov, E. (2013). Kelvin-Helmholtz instabilities at the sloshing cold fronts in the Virgo cluster as a measure for the effective ICM viscosity. The Astrophysical journal, 764(1), https://doi.org/10.1088/0004-637X/764/1/60
DOI https://doi.org/10.1088/0004-637X/764/1/60
Keywords Cosmology and Nongalactic Astrophysics; High Energy Astrophysical Phenomena
Publisher URL https://iopscience.iop.org/article/10.1088/0004-637X/764/1/60/
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