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Models & Observations galaxy clusters Gabriella De Lucia

Models & Observations galaxy clusters Gabriella De Lucia. Max-Planck Institut für Astrophysik. Ringberg - October 28, 2005. Outline:. Semi-analytic models -- substructures & galaxies -- hybrid models – methods, limits & aims -- applications

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Models & Observations galaxy clusters Gabriella De Lucia

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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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