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Galaxy Clusters: Modeling Observations and Evolutionary Insights

Explore semi-analytical and hybrid models in galaxy clusters, observing color-magnitude relations, halo galaxies, satellite galaxies, star formation feedback, and more. Understand the formation and evolution of elliptical galaxies and their mass distribution across different environments. Discover the relationship between galaxy properties, feedback mechanisms, and the cosmic evolution of clusters.

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Galaxy Clusters: Modeling Observations and Evolutionary Insights

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  1. Models & Observations galaxy clusters Gabriella De Lucia Max-Planck Institut für Astrophysik Ringberg - October 28, 2005

  2. Outline: • Semi-analytic models • -- substructures & galaxies • -- hybrid models – methods, limits & aims • -- applications • The ESO Distant Cluster Survey (EDisCS) • -- the colour-magnitude relation • -- cluster structure

  3. Central galaxy CDM CDM Halo galaxy Satellite galaxy Springel et al. (2001) Mathis H. et al., 2002 De Lucia et al., MNRAS, 2004 The SAM – the hybrid models:

  4. Metallicity dependence (Sutherland & Dopita 1993) It is important!! (Tissera & Scannapieco 2003) re-incorporation cooling Cold Gas Hot Gas star formation feedback recycling Stars Ejected Gas The SAM – the physics: DLG, Kauffmann & White, 2004

  5. B-V > 0.8 B-V < 0.8 4 Mpc A simulated cluster (M ~ 1015 M) DM density map Cluster galaxies Gabriella De Lucia, PhD Thesis

  6. Tully-Fisher Colour-magnitude DLG, Kauffmann & White, 2004 Luminosity function Gas fraction-luminosity Metallicity-mass

  7. hot gas stars gas The field metal budget ej. slow wind slow ejected Observational signature of different feedback models #2: retention ej. fast Differences between different models become more dramatic at high redshifts Mass metals / Y * Mstar 1+redshift DLG, Kauffmann & White, 2004

  8. EDisCS clusters A wide range of masses and structural properties White et al., A&A, in press

  9. 3 5 single burst z=3 exp. s.f.r. z=3 spec. conf. members The CM of 2 EDisCS clusters De Lucia et al., ApJL, 2004

  10. deficit De Propris et al.(2003) The red-sequence LF V-rest Coma Composite EDisCS @z=0.75 Number of galaxies I-obs V Robust result – also present in the full photometric catalogue! De Lucia et al., ApJL, 2004 (see also Kodama et al. 2004)

  11. EDisCS clusters #lum/#faint A496 Coma redshift The build-up of the CM relation There is a clear increase in the luminous-to-faint ratio with increasing redshift De Lucia et al., in prep. A “cosmic down-sizing” (Cowie, 1996). A problem for the hierarchical paradigm?

  12. In a ‘minor’ merger the stellar mass of the merged galaxy is transferred to the bulge of the central galaxies + burst of a fraction of the combined cold gas • A ‘major’ merger completely destroys the disc of the central galaxy + burst of a fraction of the remaining gas • Disk instability (Mo, Mao & White 1998) Ellipticals in our hierarchical model • AGN model for suppression of the cooling-flows (Croton et al., 2005) Three channels to make bulges: De Lucia et al., astro-ph/0509725 1,031,049 (810,486 ) Es with Mstar > 4x109 (1x1010) Msun 16% Es / 66% Sp / 18 % S0 (MV < -18) (13%, 67%, 20% Loveday et al., 1996)

  13. Gallazzi et al., in preparation The origin of the colour-magnitude increasing Z increasing age Brighter ellipticals are older AND more metal rich De Lucia et al., in preparation

  14. redshift clusters cluster 1010M 1011M 1012M Mstar = 1012 Msun Mstar = 109 Msun field field Lookback time (Gyr) Lookback time (Gyr) The star formation histories: mass cluster ellipticals field ellipticals Elliptical galaxies also have a shorter formation timescale! This is “anti-hierarchical”!!! De Lucia et al., astro-ph/0509725

  15. M200 = 1015 Msun M200 = 1012 Msun The “double-downsizing” (see talk by T. Treu) A natural expectation in the hierarchical scenario redshift Elliptical galaxies in denser environment are older Lookback time (Gyr) De Lucia et al., astro-ph/0509725

  16. 50 % stars in a single object 50 % stars formed Fraction of galaxies 80 % 80 % redshift redshift Ellipticals: formation & assembly De Lucia et al., astro-ph/0509725

  17. Simulation z=0.398 cl1018-1211 z=0.472 1’ 1 Mpc Simulation z=0.783 cl1216-1201 z=0.795 Simulated and real clusters Full information about the spatial and redshift distribution of model galaxies construction of simulated catalogues of galaxies including luminosity, colour, bulge-to-disc ratio etc.

  18. Model results can be treated with exactly the same methods used for the observational data Observing a simulated cluster

  19. Structure comparison a simulated cl @ z=0.8 De Lucia et al., in preparation cl1216-1201 @ z= 0.8

  20. Conclusions: • Semi-analytic models are atechniquefor studying galaxy formation - they arenot meant to be definitive! • The ever more detailed picture of our Universe also requires a more complex modelling • An apparent “down-sizing” in the formation of elliptical galaxies is not in contradiction with the hierarchical paradigm • A self-consistent approach that takes into account the spectro-photometric AND chemical evolution is necessary • Comparison with observational results (expecially at high redshifts) will provide important constraints on physical processes and missing physics. • CM of EDisCS clusters: a clear increase of the Lum/Faint ratio for passive red galaxies as a function of redshift

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