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Galaxy Cluster Morphology: Formation and Interactions Analysis at Ringberg 2005

Explore the connection between galaxy clusters and individual galaxies, focusing on structure formation like dark matter and hot gas. Investigate how galaxies and intergalactic medium are affected during cluster formation stages. Analyze by measuring centroid offset, ellipticity, and position angle. Utilize X-ray and optical imaging to assess cluster structure. Discuss observations from NASA press release and potential cluster 'age' determination methods. Future research directions include addressing errors and advancing techniques for higher redshift analysis.

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Galaxy Cluster Morphology: Formation and Interactions Analysis at Ringberg 2005

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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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