zCOSMOS galaxy clustering: status and perspectives Sylvain de la Torre Marseille - June, 11th Clustering working group: Ummi Abbas, Sylvain de la Torre, Baptiste Meneux, Cristiano Porciani

2 Analysis using 10K sample luminosity and stellar mass Galaxy clustering / luminosity and stellar mass (Meneux at al.)  submitted and ~accepted (on astro-ph today) morphology Galaxy clustering / morphology (de la Torre at al.)  to be submitted (currently on zCOSMOS TBS wiki page) color Galaxy clustering / color (Porciani at al.)  to be posted on the TBS wiki page very soon environment Galaxy clustering / environment (Abbas at al.)  on-going

3 Galaxy clustering / morphology elliptical more strongly clustered The elliptical galaxies are always more strongly clustered independently of the luminosities since z~0.9 decreases with redshift Some indications that the segregation in morphological type slowly decreases with redshift at a given luminosity morphology-density relation This observed trend is coherent with the time evolution of the morphology-density relation Redshift Luminosity de la Torre et al., 2009

4 Galaxy clustering / morphology Redshift Luminosity de la Torre et al., 2009 Mean and the dispersion of w p (r p ) obtained among 30 random realisations of the ”homogenisation” removes the morphological segregation of clustering The approximate procedure essentially removes the morphological segregation of clustering at all scales (<10 Mpc) morphological segregation of galaxy clustering morphology-density same (environmental) effect This supports that the morphological segregation of galaxy clustering and the morphology-density relation are two manifestations of the same (environmental) effect  Indication of an origin in relation to local environment

5 Galaxy clustering / luminosity Any clear dependence on luminosity Any clear dependence on luminosity of the correlation function at 0.2<z<1.0 At odd with results in the local Universe At odd with results in the local Universe (e.g. 2dFGRS) and with mesurements at similar redshift by the VVDS and DEEP2 surveys, that found a significant steepening of w p (r p ) with luminosity. Meneux et al., 2009

6 Galaxy clustering / stellar mass Meneux et al., 2009 more evident dependence of w p (r p ) on stellar mass Mildly more evident dependence of w p (r p ) on stellar mass, especially on small scales any significant evolution with redshiftof clustering for massive galaxies We do not see any significant evolution with redshift of the amplitude of clustering for massive galaxies (comp. to SDSS). This is consistent with a more rapid evolution of the linear bias for the most massive objects

7 Galaxy clustering / environment Abbas et al., 2009 (in prep.) 35% highest/lowest δ 25% highest/lowest δ zCOSMOS 10K SDSS (Abbas et al. 2007)

8 zCOSMOS limitation for clustering Sample (cosmic) variance: Sample (cosmic) variance: the presence of a large number of rich structure in the field prevents us from reaching to “universal” conclusions on clustering. excess of power (“shoulder”) at scales > 1-2 Mpc/h  Systematic effect in the measurement of the correlation functions: excess of power (“shoulder”) at scales > 1-2 Mpc/h This effect prevents us from performing “standard” HOD modeling, or to make robust measurements of the galaxy absolute bias (using CF)

9 Perspectives using 20K sample basic measurements done with the 10K sample Redo the basic measurements done with the 10K sample (different galaxy property dependencies on clustering) impact of local structures Better understand the impact of local structures on galaxy clustering measurements (maybe modeling them using HOD) HOD modeling Perform HOD modeling to infer on properties of the hosting halos: need to use a more complex HOD modeling to account for the “peculiarity” of the sample redshift-space distortions growth parameter f(Ω) Try to measure redshift-space distortions and bring some constraints on structure growth parameter f(Ω)

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11 Relative bias of early- to late-type Expectations for different models of galaxy formation bias:  The results support a locally biased galaxy formation scenario Redshift Luminosity Narayanan et al. (2000) de la Torre et al., 2009