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Connecting Galaxy Groups with Dark Matter Haloes

This workshop explores the connection between galaxy groups and dark matter haloes, using semi-analytical models, halo occupation models, and gas dynamical simulations. The aim is to understand the clustering and properties of galaxies within these groups.

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Connecting Galaxy Groups with Dark Matter Haloes

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  1. Connecting Galaxy Groups with dark matter haloes Xiaohu Yang Shanghai Astronomical Observatory Collaborators: H.J. Mo (UMass), Frank C. van den Bosch (MPIA), S.M. Weinmann (UZurich) 7th Sino-German Workshop, Shanghai

  2. Galaxies form in the dark matter halos Semi-analytical models Halo Occupation models/conditional luminosity function Gas dynamical simulations Dark matter not directly observable Haloes may host more than 1 galaxies More direct Observational probes? Cosmic density field Dark halos Galaxies Why need galaxy groups 1. Galaxy-galaxy lensing 2. Satellite dynamics 3. Groups with properly estimated halo masses 7th Sino-German Workshop, Shanghai

  3. Galaxy Groups (including Clusters, groups and isolated galaxies) – dark matter halos 7th Sino-German Workshop, Shanghai

  4. Galaxy Groups - dark matter halos • To better understand the clustering of galaxies. • The power law of galaxy 2PCF. • eg. Jing et al. 1998 • The departure from power law (2pcf) • Zehavi et al. 2004; Yang et al. 2005b • The 3PCF • Kayo et al. 2004; Wang et al. 2004; … • Probe the group (halo) properties • Abundance; Spatial distribution; M/L relation • Bahcall et al. 2003; Padilla et al. 2004; Yang et al. 2005b,c • Eke et al. 2005; van den Bosch et al. 2005; Tinker et al. 2006 7th Sino-German Workshop, Shanghai

  5. Continue-- • Probe the galaxy properties in the groups • The halo Occupations, the Conditional Luminosity Function • e.g. Berlind & Weinberg 2002; Yang et al. 2003; Zheng et al. 2005 • The spatial distribution of galaxies in groups • Lin et al. 2004; Collister & Lahav 2005; Yang et al. 2005d • Color/type, star formation, morphology • Weinmann et al. 2005 • Can be compared with the SAM/SPH models… 7th Sino-German Workshop, Shanghai

  6. How to find (halo-based) galaxy groups • A halo-based group finder (Yang et al. 2005a) 7th Sino-German Workshop, Shanghai

  7. Test the group finder with mock galaxy distributions Halo mass; Halo radius; Velocity dispersion; Luminosity of the group; Luminosity for each galaxy; Galaxy type; Spacial distribution. 7th Sino-German Workshop, Shanghai

  8. The performance of the group finder Example: < 20% interloper > 80% completeness 7th Sino-German Workshop, Shanghai

  9. Dynamic mass (velocity dispersion of satellite galaxies) Luminosity trace total mass? Stellar mass trace total mass? Use the ranked mass tracer and the halo mass function to obtain group (halo) mass. group (halo) mass estimator 7th Sino-German Workshop, Shanghai

  10. Bias of groups/dark matter haloes Some properties of Groups b  r0 ^{/2}; d --> M_h; r0  d ^{0.75};s0  d ^{0.61}; 7th Sino-German Workshop, Shanghai

  11. The age dependence of halo bias Gao et al. 2005 Yang et al. 2005 7th Sino-German Workshop, Shanghai

  12. The conditional luminosity function 7th Sino-German Workshop, Shanghai

  13. The spatial distribution of galaxies 7th Sino-German Workshop, Shanghai

  14. The color dependent spatial distribution Collister & Lahav 2004 Red: c=3.9 \pm 0.5 Blue: c=1.3 \pm 0.2 c: NFW profile concentration 7th Sino-German Workshop, Shanghai

  15. The type fraction of galaxies 7th Sino-German Workshop, Shanghai

  16. The type fraction of satellite galaxies 7th Sino-German Workshop, Shanghai

  17. Recover the real space clustering of galaxies Model the galaxy-galaxy lensing signals using galaxy groups A Few future projects 7th Sino-German Workshop, Shanghai

  18. Recover the real space clustering of galaxies \beta=\Omega_m^0.6 / b The velocity dispersion of galaxies within groups 7th Sino-German Workshop, Shanghai

  19. Model the galaxy-galaxy lensing using galaxy groups The GMCCF around satellite galaxies 7th Sino-German Workshop, Shanghai

  20. Results from numerical simulations Around satellite galaxies: Fit with 4 parameters (M_h, c_h, R_s, M_s) c_s=10 7th Sino-German Workshop, Shanghai

  21. Recovered host halo mass 7th Sino-German Workshop, Shanghai

  22. Recovered subhalo mass for satellite of different luminosity Apply to SDSS observations… 7th Sino-German Workshop, Shanghai

  23. The type definition Weinmann et al. 2005 Early: red & passive Late: blue & active Intermediate: red & active Others: blue & passive 7th Sino-German Workshop, Shanghai

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