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Galaxy Surveys @ OABo

Galaxy Surveys @ OABo. “ The Galaxy Mass Assembly History: from 10k to 20k zCOSMOS ”. Lucia Pozzetti INAF Osservatorio Astronomico di Bologna. Mass-assembly downsizing. LP et al.+ 09. mass-dependent evolution of the number/mass density: Massive tail is present up to z=1.

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Galaxy Surveys @ OABo

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  1. Galaxy Surveys @ OABo “The Galaxy Mass Assembly History: from 10k to 20k zCOSMOS” Lucia Pozzetti INAF Osservatorio Astronomico di Bologna

  2. Mass-assembly downsizing LP et al.+ 09 mass-dependent evolution of the number/mass density: Massive tail is present up to z=1. Continuous evolution for intermediate/low-mass galaxies Mass assembly is earlier in more massive galaxies in contrast with hierarchical models

  3. MERGING FRACTIONS vs. SFH MASS GROWTH Merging fraction to explain the evolution of the global MF Merging fraction after accounting for mass growth evolution due to the SFH(M) to explain remaining differences in observed and evolved MFs.

  4. Stellar Mass Function by types MFs by colors/morphologies:Red/E+Bulge(ETGs)vs.Blue/Sp+Irr (LTGs) Trasformation of blue/active into red/passive galaxies MFs by SSFR: SSFR<10-10 vs. SSFR>10-10

  5. Cimatti et al. 06 (Scarlata et al. 07) Evolution of LF of ETGs Increase with cosmic time since z=1 of the number densities of intermediate-L ETGs. Mass-assembly downsizing for ETGs in contrast with hierarchical models by De Lucia et al. 2006

  6. Formation of stars constraints from present-day ETGs galaxies Constraints on age/SFH from σ, Hβ, Mgb, <Fe>, stellar populations Thomas et al. 2004 See also: Bernardi et al. 98,03-04 Kuntschner et al. 02 Pipino & Matteucci 2004 +MANY others….. See Schiavon et al. 2006 for a different view… => ETGs dominated by old stellar populations => More massive spheroids form earlier and faster => Formation time scales independent of environment ~1-2 Gyr younger in low density environments => Mass assembly almost completed around z~1

  7. Evolution of the MF of ETGs ETGsdefined using different criteria (colors, morphology, spectral features, SFR or an intersection of them) Increase with cosmic time since z=1 of the number densities of intermediate-mass ETGs. Mass-assembly downsizing for ETGs in contrast with hierarchical models

  8. E/S0 galaxies: hierarchical merging predictions “Millennium Simulation” N-body + semi-analytic model (Springel et al. 2005) Assembly redshift = redshift when 50% of the final stellar mass is contained in a single object More massive galaxies assemble later The final assembly is reached at z<1 for the massive galaxies De Lucia et al. 2005 M>1011 Msun M>4x109 Msun Mass-assembly up-sizing for ETGs in hierarchical models

  9. Building redshift of ETGs z-building = Redshift at which the number density decreases by a factor 2 from redshift zero z-building increases with mass in contrast with hierarchical models

  10. SAM prediction for ETGs MFs • Hierarchical models : • Underpredict of luminous/red/massive galaxies at high-z • Overpredict low-Luminosity/Masses galaxies at all redshifts

  11. From 10k to 20k bright sample • Better constraints : • on ETGs growth rate, merging fractions and quenching fractions • New Analysis: • - Derivation of total Mass (Mstar+Mgas) MFs • [using the inversion of Kennicutt-Schimdt relation to derive Mgas or gas content (M) (from HI) up to the redshift observed (as lower limit !?). • - Comparison with hierarchical barionic MFs and halo MFs

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