How does our choice of observable influence our estimation of the centre of a galaxy cluster? Insights from cosmological simulations
Date Issued
2016
Author(s)
Cui, Weiguang
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Power, Chris
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Knebe, Alexander
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Lewis, Geraint F.
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Poole, Greg B.
Abstract
Galaxy clusters are an established and powerful test-bed for theories of both galaxy evolution and cosmology. Accurate interpretation of cluster observations often requires robust identification of the location of the centre. Using a statistical sample of clusters drawn from a suite of cosmological simulations in which we have explored a range of galaxy formation models, we investigate how the location of this centre is affected by the choice of observable - stars, hot gas, or the full mass distribution as can be probed by the gravitational potential. We explore several measures of cluster centre: the minimum of the gravitational potential, which would expect to define the centre if the cluster is in dynamical equilibrium; the peak of the density; the centre of brightest cluster galaxy (BCG); and the peak and centroid of X-ray luminosity. We find that the centre of BCG correlates more strongly with the minimum of the gravitational potential than the X-ray defined centres, while active galactic nuclei feedback acts to significantly enhance the offset between the peak X-ray luminosity and minimum gravitational potential. These results highlight the importance of centre identification when interpreting clusters observations, in particular when comparing theoretical predictions and observational data.
Volume
456
Issue
3
Start page
2566
Issn Identifier
0035-8711
Ads BibCode
2016MNRAS.456.2566C
Rights
open.access
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