How does our choice of observable influence our estimation of the centre of a galaxy cluster? Insights from cosmological simulations

Weiguang Cui, Chris Power, V. Biffi, S. Borgani, G. Murante, D. Fabjan, A. Knebe, G.F. Lewis, G.B. Poole

Research output: Contribution to journalArticle

18 Citations (Scopus)

Abstract

© 2015 The Authors. 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.
Original languageEnglish
Pages (from-to)2566-2575
JournalMonthly Notices of the Royal Astronomical Society
Volume456
Issue number3
DOIs
Publication statusPublished - 2016

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galaxies
gravitational fields
simulation
cosmology
luminosity
prediction
gas
x rays
test stands
galactic evolution
high temperature gases
mass distribution
active galactic nuclei
centroids
stars
predictions
test
distribution

Cite this

Cui, Weiguang ; Power, Chris ; Biffi, V. ; Borgani, S. ; Murante, G. ; Fabjan, D. ; Knebe, A. ; Lewis, G.F. ; Poole, G.B. / How does our choice of observable influence our estimation of the centre of a galaxy cluster? Insights from cosmological simulations. In: Monthly Notices of the Royal Astronomical Society. 2016 ; Vol. 456, No. 3. pp. 2566-2575.
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How does our choice of observable influence our estimation of the centre of a galaxy cluster? Insights from cosmological simulations. / Cui, Weiguang; Power, Chris; Biffi, V.; Borgani, S.; Murante, G.; Fabjan, D.; Knebe, A.; Lewis, G.F.; Poole, G.B.

In: Monthly Notices of the Royal Astronomical Society, Vol. 456, No. 3, 2016, p. 2566-2575.

Research output: Contribution to journalArticle

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AU - Cui, Weiguang

AU - Power, Chris

AU - Biffi, V.

AU - Borgani, S.

AU - Murante, G.

AU - Fabjan, D.

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AU - Lewis, G.F.

AU - Poole, G.B.

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AB - © 2015 The Authors. 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.

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