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Galaxy Formation in a LCDM Universe. Qi Guo Max Planck Institute for Astrophysics. Kunming, Feb 24th. 2009. Outline. Millennium Run and Millennium Run II Semi-analytic models Results: Stellar mass function Dwarf galaxies in the Milky Way Color vs. stellarmass relations
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Galaxy Formation in a LCDM Universe QiGuo Max Planck Institute for Astrophysics Kunming, Feb 24th. 2009
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
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
Millennium Simulation II z=0 Boylan-Kolchin et al. (2009) 100Mpc/h
Galaxy cluster in MRII 5Mpc/h
Dark matter Halo mass functions Boylan-Kolchin et al. (2009)
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
Stellar Mass Function: MR+MRII
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)
Stellar Mass Function: MR+MRII
Stellar Mass Function: MR+MRII
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
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
Color vs. Stellar Mass: De Lucia & Blaizot (2007) New SAM
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
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 …..
Carina, Draco, Fornax, LMC, LeoI, LeoII, Ursa Minor, SMC, Sculptor, Sextans, Sagittarius
SN Feedback 0.3* SN feedback Reincorporation