The DEEP2 galaxy redshift survey: Clustering of galaxies in early data

We measure the two-point correlation function ε(r_p, π) in a sample of 2219 galaxies between z = 0.7 and 1.35 to a magnitude limit of R_AB = 24.1 from the first season of the DEEP2 Galaxy Redshift Survey. From ε(r_p, π) we recover the real-space correlation function, ε(r), which we find can be approximated within the errors by a power law, ε(r) = (r/r₀]^-γ, on scales ∼0.1-10 h^-1 Mpc. In a sample with an effective redshift of z _eff = 0.82, for a ACDM cosmology we find r₀ = 3.53 ± 0.81 h^-1 Mpc (comoving) and γ = 1.66 ± 0.12, while in a higher redshift sample with z_eff = 1.14 we find r ₀ = 3.12 ±0.72 h^-1 Mpc and γ = 1.66 ± 0.12. These errors are estimated from mock galaxy catalogs and are dominated by the cosmic variance present in the current data sample. We find that red, absorption-dominated, passively evolving galaxies have a larger clustering scale length, r₀, than blue, emission-line, actively star-forming galaxies. Intrinsically brighter galaxies also cluster more strongly than fainter galaxies at z ≃ 1. Our results imply that the DEEP2 galaxies have an effective bias b = 0.96 ± 0.13 if σ_8DM = 1 today or b = 1.19 = 0.16 if σ_8DM = 0.8 today. This bias is lower than that predicted by semianalytic simulations at z ≃ 1, which may be the result of our R-band target selection. We discuss possible evolutionary effects within our survey volume, and we compare our results with galaxy-clustering studies at other redshifts, noting that our star-forming sample at z ≃ 1 has selection criteria very similar to the Lyman break galaxies at z ≃ 3 and that our red, absorption-line sample displays a clustering strength comparable to the expected clustering of the Lyman break galaxy descendants at z ≃ 1. Our results demonstrate that galaxy-clustering properties as a function of color, spectral type, and luminosity seen in the local universe were largely in place by z ≃ 1.