On the width of cold fronts in clusters of galaxies due to conduction

Abstract

We consider the impact of thermal conduction in clusters of galaxies on the (unmagnetized) interface between a cold gaseous cloud and a hotter gas flowing over the cloud (the so-called cold front). We argue that near the stagnation point of the flow conduction creates a spatially extended layer of constant thickness $\Delta$, where $\Delta$ is of order $\sim \sqrt{kR/U}$, and $R$ is the curvature radius of the cloud, $U$ is the velocity of the flow at infinity, and $k$ is the conductivity of the gas. For typical parameters of the observed fronts, one finds $\Delta \ll R$. The formation time of such a layer is $\sim R/U$. Once the layer is formed, its thickness only slowly varies with time and the quasi-steady layer may persist for many characteristic time scales. Based on these simple arguments one can use the observed width of the cold fronts in galaxy clusters to constrain the effective thermal conductivity of the intra-cluster medium.

Accepted for MNRAS. 9 pages; 6 b&w figures; 2 colour figures

References in corpus (4)

• Shocks and cold fronts in galaxy clusters
• The origin of cold fronts in the cores of relaxed galaxy clusters
• Magnetic draping of merging cores and radio bubbles in clusters of galaxies
• Thermal conduction in cosmological SPH simulations

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• The Merger Dynamics of the X-ray Emitting Plasma in Clusters of Galaxies