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Galaxy Formation Dynamics in a ΛCDM Universe: Insights from Millennium Simulations

This presentation discusses findings from the Millennium and Millennium II simulations relating to galaxy formation within a Lambda Cold Dark Matter (ΛCDM) model. It covers semi-analytical models, stellar mass functions, and the characteristics of dwarf galaxies in the Milky Way, including gas metallicities and their implications for star formation and evolution. Key results highlight the role of dark matter, feedback mechanisms, and the correlation between stellar mass and halo mass. Potential implications for understanding galaxy morphology and evolution are also explored.

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Galaxy Formation Dynamics in a ΛCDM Universe: Insights from Millennium Simulations

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  1. Galaxy Formation in a LCDM Universe QiGuo Max Planck Institute for Astrophysics Kunming, Feb 24th. 2009

  2. Outline • Millennium Run and Millennium Run II • Semi-analytic models • Results: • Stellar mass function • Dwarf galaxies in the Milky Way • Color vs. stellarmass relations • Gas metallicities

  3. Simulations • Cosmology (2dFGRS & WMAP1y): • Ωm = Ωdm + Ωb = 0.25, Ωb = 0.045, ΩΛ = 0.75 • H = 73km/s/Mpc • n=1 • σ8 = 0.9 • MR • Particle number 2160^3 • Box size 500/h Mpc • Particle mass 8.6*10^8Msun • Z 127~0 • MRII • Particle number 2160^3 • Box size 100/h Mpc • Particle mass 6.8*10^6Msun • Z 127~0

  4. Millennium Simulation z=0

  5. Millennium Simulation II z=0 Boylan-Kolchin et al. (2009) 100Mpc/h

  6. Galaxy cluster in MRII 5Mpc/h

  7. Dark matter Halo mass functions Boylan-Kolchin et al. (2009)

  8. Galaxy Formation: • Dark matter dynamics • Cooling (temperature, metallicity,…) • Star formation and evolution (molecular formation, disk size..) • Feedback (SN feedback, AGN feedback …) • Gas reincorporation • Chemical evolution • Dust extinction • Mergers and Disruption • Black Holes

  9. Stellar Mass Function: MR+MRII

  10. Galaxy Formation: • Dark matter dynamics • Cooling (temperature, metallicity,…) • Star formation and evolution (molecular formation, disk size..) • Feedback (SN feedback, AGN feedback …) • Gas reincorporation • Chemical evolution • Dust extinction • Mergers and Disruption • Black Holes Reincorporation Feedback (reheating) Cooling Feedback (ejection)

  11. Stellar Mass Function: MR+MRII

  12. Stellar Mass Function: MR+MRII

  13. Stellar mass vs Dark matter Halo mass relation: M_200 = Func (M_star) SAM + MRII N (M_200 > Mh) = N (M_gal > M_star) SDSS + MRII+MR

  14. Luminosity Function in the Milky Way: Cumulative luminosity function of satellites of model Milky-Way-like galaxies. Cumulative luminosity function of the ten classical satellites of the Milky Way

  15. Color vs. Stellar Mass: De Lucia & Blaizot (2007) New SAM

  16. Gas Metallicity: 12+log[O/H] 9.4 9.2 9.0 8.8 8.6 8.4 8.2 8.0 Tremonti et al. (2004) 8 9 10 11 8 9 10 11 12 Log(M/M_sun) De Lucia & Blaizot (2007) New SAM

  17. To summarize • Strong SN feedback and long time scale of reincorporation are needed to reproduce the right slope and the right amplitude of the low mass end of galaxy stellar mass function. • Model galaxies have the expected stellar masses in given dark matter halos. • The satellite luminosity function for galaxies as the Milky Way is automatically reproduced. • The new models improve the stellar mass vs. B-V color relation and stellar mass vs. gas metallicity relation. • Some more to understand: color dispersion in B-V color; • gas metallicity at high mass end; ages; stellar mass • correlation functions …..

  18. Carina, Draco, Fornax, LMC, LeoI, LeoII, Ursa Minor, SMC, Sculptor, Sextans, Sagittarius

  19. SN Feedback 0.3* SN feedback Reincorporation

  20. Stellar Mass Correlation:

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