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Galaxy Clustering and Galaxy Bias in a ΛCDM Universe

Please use this identifier to cite or link to this item: http://hdl.handle.net/1811/47797

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dc.creator Weinberg, David H.
dc.creator Davé, Romeel
dc.creator Katz, Neal
dc.creator Hernquist, Lars
dc.date.accessioned 2011-02-02T16:12:18Z
dc.date.available 2011-02-02T16:12:18Z
dc.date.issued 2004-01-20
dc.identifier.citation David H. Weinberg et al, "Galaxy Clustering and Galaxy Bias in a ΛCDM Universe," The Astrophysical Journal 601, no. 1 (2004), doi:10.1086/380481 en_US
dc.identifier.issn 1538-4357
dc.identifier.uri http://hdl.handle.net/1811/47797
dc.description.abstract We investigate galaxy clustering and the correlations between galaxies and mass in the ΛCDM cosmological model (inflationary cold dark matter with Ω_m = 0.4, Ω_Λ = 0.6, h = 0.65, n = 0.95, and σ_8 = 0.8), using a large, smoothed particle hydrodynamics simulation (SPH; with 2 × 144^3 particles in a 50 h^-1 Mpc cube). Simulated galaxies can be unambiguously identified as clumps of stars and cold gas a few kpc to a few tens of kpc across, residing in extended halos of hot gas and dark matter; the space density of the resolved galaxy population at z = 0 corresponds to that of observed galaxies with luminosity L ~> L*/4. We investigate the galaxy correlation function, the pairwise velocity dispersion and mean pairwise velocity, and the second and third moments of counts in cells; we also investigate the galaxy-mass correlation function and the average extended mass distributions around galaxies, both of which can be measured via galaxy-galaxy lensing. For the most part, the predicted biases between galaxies and dark matter lead to good agreement with current observations, including (1) a nearly constant comoving correlation length from z = 3 to 0 for mass-selected galaxy samples of constant comoving space density; (2) an rms bias factor b_σ approx 1 at z = 0; (3) a scale-dependent bias on small scales that transforms the curved dark matter correlation function into a nearly power-law galaxy correlation function; (4) galaxy pairwise dispersion and hierarchical skewness ratio S_3 in good agreement with observed values, lower than values for the dark matter by ~20%; (5) a ratio of galaxy-galaxy to galaxy-mass correlation functions consistent with recent measurements from the Red Cluster Sequence survey; and (6) a mean excess mass ΔM(260 h^-1 kpc) approximately proportional to galaxy baryon mass M_b, in agreement with estimates from the Sloan Digital Sky Survey (SDSS). All these clustering properties vary with galaxy baryon mass and, more strongly, with the age of a galaxy's stellar population. The predicted dependences are in good qualitative agreement with the observed dependence of galaxy clustering and the galaxy-mass correlation function on galaxy type. The predicted ratio ΔM(260 h^-1 kpc)/M_b is lower than the SDSS estimates by a factor of ~1.5-3 for galaxies with M_b ~> 2 × 10^11 Msun. A test with a higher resolution (smaller volume) simulation suggests that this discrepancy is largely a numerical artifact; if so, then the SDSS weak-lensing comparison leaves limited room for feedback or other astrophysical processes to reduce the stellar masses of luminous galaxies, at least given our adopted cosmological parameters. On the whole, our results show that the ΛCDM model and the galaxy formation physics incorporated in the SPH simulation give a good account of observed galaxy clustering, but anticipated improvements in clustering and weak-lensing measurements will soon test this picture in much greater detail. en_US
dc.language.iso en_US en_US
dc.publisher American Astronomical Society en_US
dc.subject cosmology: theory en_US
dc.subject galaxies: formation en_US
dc.subject large-scale structure of universe en_US
dc.subject methods: numerical en_US
dc.title Galaxy Clustering and Galaxy Bias in a ΛCDM Universe en_US
dc.type Article en_US
dc.identifier.doi 10.1086/380481
dc.identifier.osuauthor weinberg.21