We measure the luminosity and color dependence of galaxy clustering in the largest-ever galaxy redshift survey , the main galaxy sample of the Sloan Digital Sky Survey ( SDSS ) Seventh Data Release ( DR7 ) .
We focus on the projected correlation function { w _ { p } ( r _ { p } ) } of volume-limited samples , extracted from the parent sample of \sim 700 , 000 galaxies over 8000 deg ^ { 2 } , extending up to redshift of 0.25 .
We interpret our measurements using halo occupation distribution ( HOD ) modeling assuming a \Lambda CDM cosmology ( inflationary cold dark matter with a cosmological constant ) .
The amplitude of { w _ { p } ( r _ { p } ) } grows slowly with luminosity for L < L _ { * } and increases sharply at higher luminosities , with a large-scale bias factor b ( > L ) \times ( \sigma _ { 8 } / 0.8 ) = 1.06 + 0.21 ( L / L _ { * } ) ^ { 1.12 } , where L is the sample luminosity threshold .
At fixed luminosity , redder galaxies exhibit a higher amplitude and steeper correlation function , a steady trend that runs through the “ blue cloud ” and “ green valley ” and continues across the “ red sequence. ” The cross-correlation of red and blue galaxies is close to the geometric mean of their auto-correlations , dropping slightly below at r _ { p } < 1 h ^ { -1 } { Mpc } .
The luminosity trends for the red and blue galaxy populations separately are strikingly different .
Blue galaxies show a slow but steady increase of clustering strength with luminosity , with nearly constant shape of { w _ { p } ( r _ { p } ) } .
The large-scale clustering of red galaxies shows little luminosity dependence until a sharp increase at L > 4 L _ { * } , but the lowest luminosity red galaxies ( 0.04 - 0.25 L _ { * } ) show very strong clustering on small scales ( r _ { p } < 2 h ^ { -1 } { Mpc } ) .
Most of the observed trends can be naturally understood within the \Lambda CDM+HOD framework .
The growth of { w _ { p } ( r _ { p } ) } for higher luminosity galaxies reflects an overall shift in the mass scale of their host dark matter halos , in particular an increase in the minimum host halo mass M _ { min } .
The mass at which a halo has , on average , one satellite galaxy brighter than L is M _ { 1 } \approx 17 M _ { min } ( L ) over most of the luminosity range , with a smaller ratio above L _ { * } .
The growth and steepening of { w _ { p } ( r _ { p } ) } for redder galaxies reflects the increasing fraction of galaxies that are satellite systems in high mass halos instead of central systems in low mass halos , a trend that is especially marked at low luminosities .
Our extensive measurements , provided in tabular form , will allow detailed tests of theoretical models of galaxy formation , a firm grounding of semi-empirical models of the galaxy population , and new constraints on cosmological parameters from combining real-space galaxy clustering with mass-sensitive statistics such as redshift-space distortions , cluster mass-to-light ratios , and galaxy-galaxy lensing .