Work

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

Year: 2004

Type: article

Abstract: 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 I AB magnitude and ( R - I ) color to a depth of I AB = 24 on scales θ = 7''-3', using a sample of ~350,000 galaxies covering 5 deg 2 in total over five separate fields. Using redshifts of 2954 galaxies in early DEEP2 Galaxy Redshift Survey data, we construct robust galaxy redshift distributions as a function of I AB magnitude and ( R - I ) color for galaxies in the range 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, x 0 , evolves linearly with redshift, x 0 ( z ) = x 0 (0)(1 - Bz ), fits the data better than the model proposed by Groth & Peebles. 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 x 0 = 5.0 ± 0.3 h -1 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 > 1.4 galaxies, as well as broad-line active galactic nuclei. We find that local blue dwarfs are relatively unclustered, with x 0 = 1.6 ± 0.2 h -1 Mpc. The z > 1.4 blue galaxies have a larger clustering scale length, x 0 ≳ 5 h -1 Mpc.

Source: The Astrophysical Journal

DOI: 10.1086/425676