AAS 205th Meeting, 9-13 January 2005
Session 119 Galaxy Clusters and Groups II
Oral, Wednesday, January 12, 2005, 10:00-11:30am, Pacific 2/3

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[119.05] Velocity Gradients in the ICM of the Centaurus Cluster

R. Dupke, J. Bregman (University of Michigan)

We present the analysis of the velocity structure of the ICM near the core of Abell 3526 obtained with two off-center Chandra observations, specifically designed to eliminate gain errors. We detected gas bulk motions along the direction NE-SW direction, perpendicular to the direction of the incoming sub-group Cen45, in agreement with previous ASCA SIS measurements. The velocity gradient is seen significantly with and without the inclusion of the FeK line complex in the spectral fittings. The configuration and magnitude of the velocity gradient is consistent with rotational motion with transonic circular velocities of ~ (1.2±0.1)x103 km s-1. The metal abundances in the Centaurus cluster are high enough to provide counts for the analysis of several individual lines. The error weighted average of the Fe XXIII+XXIV, Si XIV, Fe XV lines is (2.4 ±0.8)x103 km s-1 for regions 3'x3' squared roughly diametrically opposed around the cluster's core. This is the first direct confirmation of velocity gradients in the intracluster gas and indicates that strong departure from hydrostatic equilibrium are possible even for cool clusters that do not show obvious signs of merging. This work has been partially supported by NASA Grant AR4-5013X.

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The author(s) of this abstract have provided an email address for comments about the abstract: rdupke@umich.edu

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© 2004. The American Astronomical Society.