Evolution and Color-dependence of the Galaxy Angular Correlation Function: 350,000 Galaxies in 5 Square Degrees

When applied to deep photometric catalogs, the two-point angular correlation function, ω(θ), is a sensitive probe of the evolution of galaxy clustering properties. Here we present measurements of ω(θ) as a function of IAB magnitude and (R − I) color to a depth of IAB = 24 on scales θ = 7 − 3, using a sample of ∼ 350, 000 galaxies covering 5 degrees in total over 5 separate fields. Using redshifts of 3319 galaxies in early DEEP2 Galaxy Redshift Survey data, we construct robust galaxy redshift distributions as a function of IAB magnitude and (R − I) color for galaxies between 0 < z < 2. We constrain models of the redshift evolution of galaxy clustering and find that significant growth of clustering has occurred from z ≥ 1 to z = 0. A model in which the comoving scale-length, x0, evolves linearly with redshift, x0(z) = x0(0)(1 − Bz), fits the data better than the ǫ model proposed by Groth & Peebles (1977). The clustering properties depend strongly on observed (R − I) color, with both the reddest and bluest galaxies exhibiting large clustering amplitudes and steeper slopes. Different observed (R − I) color ranges are sensitive to very disparate redshift regimes. Red galaxies with (R−I) ∼ 1.5 lie in a narrow redshift range centered at z ∼ 0.85 and have a comoving scale length of clustering at z = 0.85 of x0 = 6.6± 0.3 h Mpc. These galaxies have early-type spectra and are likely progenitors of massive local ellipticals. The bluest galaxies with (R− I) ∼ 0 appear to be a mix of star-forming galaxies, both relatively local (z ∼ 0.3− 0.6) dwarfs and bright z ∼ 1.7 galaxies, and QSOs that span a wide redshift range. We find that local blue dwarfs are relatively unclustered, with x0 = 1.8±0.3 h Mpc. The z ∼ 1.7 blue galaxies have a larger clustering scale-length, x0 ∼ 5.0±0.4 h Mpc, and QSOs are strongly clustered, with x0 ∼ 9.0± 1.1 h Mpc. Subject headings: galaxies: statistics — galaxies: evolution — cosmology: large-scale structure of universe