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The morphology of clusters of galaxies: the cluster-galaxy connection

The morphology of clusters of galaxies: the cluster-galaxy connection. Irini Sakelliou. Birmingham : T. Ponman MPIA : S. Falter, V. Smolcic, E. Bell MPE : A. Finoguenov Colorado: P. Motl. How structure is formed. The formation of a Coma-like cluster. Left panels : Dark matter

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The morphology of clusters of galaxies: the cluster-galaxy connection

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  1. The morphology of clusters of galaxies:the cluster-galaxyconnection Irini Sakelliou Birmingham : T. Ponman MPIA : S. Falter, V. Smolcic, E. Bell MPE : A. Finoguenov Colorado: P. Motl

  2. How structure is formed The formation of a Coma-like cluster. Left panels : Dark matter Right panels : Hot gas Ringberg 2005

  3. Galaxy-Cluster interactions They should affect both : the cluster and its galaxies An infalling galaxy in A2125 (z~0.25) Chandra/HST/VLA/KPNO images 01-06-04 NASA press release Ringberg 2005

  4. How/when and at which stage of cluster formation a) the galaxies are affected/tranformed and b) the ICM is affected by the infalling material? Temperature maps Contours= surface brightness Ringberg 2005

  5. Simple measures of the structure. That it can work with X-ray and optical and simulated images • Centroid offset : Determination of the centre of the distribution in annuli of increasing radius. The annuli are not concentric. • Ellipticity • Position Angle Ringberg 2005

  6. Accumulation of counts (cnt) along circular annuli (). If the 2D distribution is elliptical the cnt- plot should have 2 peaks. The shape of the cnt- plot depends on the ellipticity and the position angle. Ellipticity & Position angle Ringberg 2005

  7. Abell 2255 XMM-Newton image in the (0.3 - 10.0) keV energy range (~14ks MOS exposure) Abell 2255 is a ~7keV at z=0.08 SDSS cluster galaxies. Red circle = XMM FOV Ringberg 2005

  8. High-z cluster at z=0.22 from COSMOS (Smolcic et al. 2006) It is a poor cluster, in the process of merging with other groups. X-ray contours Red cluster galaxies Blue galaxies Ringberg 2005

  9. A2255: Centroid offset X-rays: ICM distribution Optical : galaxy distribution Ringberg 2005

  10. Ellipticity & Position angle Ringberg 2005

  11. A2255: position angle Ringberg 2005

  12. Summary, Concluding remarks, & future z= 0.25 • A simple method to determine the dynamical ‘age’ of clusters from X-ray and optical observations • There are still problems to be solved (e.g., errors) • We need simple methods for determining the structure of clusters if we want to go higher redshifts • Use simulated X-ray images to set the baseline Simulated X-ray images from Motl et al.2004 z= 0.00 Ringberg 2005

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