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luminosity & color of galaxies in clusters. sarah m. hansen university of chicago with erin s. sheldon (nyu) risa h. wechsler (stanford). astrophysics with eV photons. sarah m. hansen university of chicago with erin s. sheldon (nyu) risa h. wechsler (stanford). outline. motivation
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luminosity & color of galaxies in clusters sarah m. hansen university of chicago with erin s. sheldon (nyu) risa h. wechsler (stanford)
astrophysics with eV photons sarah m. hansen university of chicago with erin s. sheldon (nyu) risa h. wechsler (stanford)
outline • motivation • sdss data & cluster sample • characterizing the galaxy population • luminosity function: dependence on cluster mass, galaxy color • blue fraction: dependence on cluster mass, redshift, galaxy luminosity & cluster-centric radius glcw8
motivation • clusters as cosmological probes • how to connect dark and luminous matter? • how to connect stars and gas? • clusters as galaxy evolution laboratories • what’s happened to form such a particular cluster galaxy population? • for upcoming large surveys, want to understand these details better glcw8
sdss clusters • > 7300 deg2 of ugriz photometric data • maxBCGclusters • red sequence matched filter (koester et al. 2007a,b) • z ≤ 0.3; Dz ~ 0.01 • mass proxy: N200 13,823 systems with N200≥ 10 and z ≤ 0.3 • mass - richness scaling • mass function & cosmological params (rozo et al. 2007) • velocity dispersion (becker et al. 2007) • lensing (sheldon et al.; johnston et al.) • x-ray (rykoff et al.) glcw8
galaxy properties BCG or not? radial distance luminosity color cluster properties richness total luminosity redshift BCG properties • luminosity function as f (richness, color) • blue fraction as f (richness, redshift, radius, luminosity) method • measure background-subtracted, k-corrected distribution of galaxies associated with clusters, binned by cluster& galaxy properties • comparison with ADDGALs simulations (wechsler et al.) glcw8
conditional luminosity function (L|M): important ingredient for understanding how galaxies populate halos glcw8
color distribution red galaxies; blue galaxies all galaxies radial color trend is due to changing number of galaxies on the red sequence vs in the blue cloud blue fraction is the info you need glcw8
blue fraction within r200 provides constraints on models of galaxy populations and evolution in clusters glcw8
blue fraction within r200 provides constraints on models of galaxy populations and evolution in clusters glcw8
blue fraction, in more detail radial trend luminosity trend glcw8
summary with sdss data and galaxy-populated simulations, we investigate the properties of cluster galaxies, including: • blue fraction as a function of cluster mass, redshift, radius and magnitude • conditional luminosity function for all, red & blue galaxies see hansen et al., arXiv:0706.soon glcw8