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Cosmology and Galaxy Evolution from Galaxy Clustering

Cosmology and Galaxy Evolution from Galaxy Clustering. Zheng Zheng Institute for Advanced Study. Outline:. Halo Occupation Distribution (HOD) Breaking the Degeneracies between Cosmology and Galaxy Bias With David Weinberg (Ohio State University) (Zheng & Weinberg, astro-ph/0512071)

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Cosmology and Galaxy Evolution from Galaxy Clustering

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  1. Cosmology and Galaxy Evolution from Galaxy Clustering Zheng Zheng Institute for Advanced Study

  2. Outline: • Halo Occupation Distribution (HOD) • Breaking the Degeneracies between Cosmology and Galaxy Bias With David Weinberg (Ohio State University) (Zheng & Weinberg, astro-ph/0512071) • Evolution of Galaxies from HOD Modeling of DEEP2 and SDSS Galaxy Clustering With Alison Coil(University of Arizona) Idit Zehavi(Case Western Reserve University)

  3. Snapshot @ z~1100 Light-Mass relation well understood CMB from WMAP Snapshot @ z~0 Light-Mass relation not well understood Galaxies from SDSS

  4. Cosmological Model initial conditions energy & matter contents Galaxy Formation Physics gas dynamics, cooling star formation, feedback m 8ns  Dark Halo Population n(M) (r|M) v(r|M) Halo Occupation Distribution P(N|M) spatial bias within halos velocity bias within halos Galaxy Clustering Galaxy-Mass Correlations

  5. Halo Occupation Distribution (HOD) • P(N|M) Probability distribution of finding N galaxies in a halo of virial mass M mean occupation <N(M)>+ higher moments • Spatial bias within halos Difference in the distribution profiles of dark matter and galaxies within halos • Velocity bias within halos Difference in the velocities of dark matter and galaxies within halos e.g., Jing & Borner 1998;Ma & Fry 2000; Peacock & Smith 2000; Seljak 2000; Scoccimarro et al. 2001; Berlind & Weinberg 2002; Yang, Mo, & van den Bosch 2003; …

  6. Cosmological Model initial conditions energy & matter contents Galaxy Formation Physics gas dynamics, cooling star formation, feedback m 8ns  Dark Halo Population n(M) (r|M) v(r|M) Halo Occupation Distribution P(N|M) spatial bias within halos velocity bias within halos Galaxy Clustering Galaxy-Mass Correlations

  7. Cosmological Model initial conditions energy & matter contents Galaxy Formation Physics gas dynamics, cooling star formation, feedback m 8ns  Dark Halo Population n(M) (r|M) v(r|M) Halo Occupation Distribution P(N|M) spatial bias within halos velocity bias within halos Galaxy Clustering Galaxy-Mass Correlations

  8. Cosmology A Cosmology B  Halo Population A Halo Population B HOD A HOD B Galaxy Clustering Galaxy-Mass Correlations A  = Galaxy Clustering Galaxy-Mass Correlations B Cosmology from Galaxy Clustering?

  9. Halo populations from distinct cosmological models Changing m with 8, ns, and  Fixed Zheng, Tinker, Weinberg, & Berlind 2002

  10. Cosmology A Cosmology B  Halo Population A Halo Population B HOD A HOD B Galaxy Clustering Galaxy-Mass Correlations A  = Galaxy Clustering Galaxy-Mass Correlations B 

  11. Flexible HOD parameterization • P(N|M) • Motivated by galaxy • formation models • Spatial bias within halos Different concentrations of galaxy distribution and dark matter distribution (c) • Velocity bias within halos vg= vvm Kravtsov et al. 2004; Zheng et al. 2005

  12. Observational quantities • Spatial Clustering • Galaxy overdensity g(r) • Group multiplicity function ngroup(>N) • 2-point and 3-point correlation function of galaxies • Dynamically Sensitive Observables • m0.6/bg • Pairwise velocity dispersion v(r) • Average virial mass of galaxy groups <Mvir(N)> • Galaxy-mass cross-correlation function • mgm(r)

  13. Constraints on HOD and cosmological parameters Changing m with 8, ns, and  Fixed

  14. Constraints on HOD parameters Changing m with 8, ns, and  Fixed

  15. Constraints on cosmological parameters Changing m only Changing 8 only Cluster-normalized Halo MF matched

  16. Influence Matrix

  17. Abazajian et al. 2005 Constraints on cosmological parameters Forecast : ~10% on m ~10% on 8 ~5% on 8 m0.75 From 30 observables of8 different statistics with 10% fractional errors

  18. Conclusion Galaxy bias and cosmology are not degenerate with respect to galaxy clustering. *HOD modeling can greatly increase the cosmological power of galaxy redshift survey by taking the advantage of high-precision clustering measurements at small and intermediate scales. *Simultaneously, using galaxy clustering data, we can constrain the HODs for different classes of galaxies, which provide valuable tests of galaxy formation models.

  19. Cosmological Model initial conditions energy & matter contents Galaxy Formation Physics gas dynamics, cooling star formation, feedback m 8ns  Dark Halo Population n(M) (r|M) v(r|M) Halo Occupation Distribution P(N|M) spatial bias within halos velocity bias within halos Galaxy Clustering Galaxy-Mass Correlations

  20. Galaxy Evolution from Galaxy ClusteringGalaxy Samples • DEEP2, z~1 (Coil et al 2006) • SDSS, z~0 (Zehavi et al 2005) • Measurements of two-point correlation functions as a function of luminosity

  21. Two-point correlation function of galaxies Excess probability w.r.t. random distribution of finding galaxy pairs at a given separation 1-halo term Central 2-halo term Satellite

  22. Scatter between galaxy luminosity and host halo mass M1 - mass of halos on average hosting one satellite galaxy above Lmin Mmin - characteristic minimum mass of halos hosting Lmin galaxies Halo Occupation Distribution For a sample of galaxies more luminous than Lmin

  23. Modeling results DEEP2 galaxies L

  24. Distribution of central galaxy luminosity

  25. Mass scales of host halos

  26. Establishing an evolution link between DEEP2 and SDSS galaxies

  27. z~1 z~1 Star Formation Merging Merging z~0 z~0 Stellar mass evolution

  28. Star formation efficiency vs Halo mass

  29. Stellar mass evolution (z~1 to z~0) as a function of halo mass

  30. z~1 Star Formation Merging z~0

  31. Fardal et al. 2006 Tentative conclusion: For central galaxies in z~0 M<1012 h-1Msun halos, ~80% of their stars form after z~1 For central galaxies in z~0 M>1012 h-1Msun halos, ~20-40% of their stars form after z~1

  32. Summary & Future Work HODs at z~1 and z~0 from modeling two-point correlation functions of DEEP2 and SDSS galaxies Evolution link through halo evolution Stellar mass evolution from z~1 to z~0 for central galaxies as a function of halo mass (pure merger vs star formation) Useful constraints to galaxy formation models Clustering measurements for galaxy samples based on stellar mass Galaxy samples at different redshifts Evolution of satellite galaxies

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