Evolution of the Angular Correlation Function

For faint photometric surveys our ability to quantify the clustering ofgalaxies has depended on interpreting the angular correlation function as afunction of the limiting magnitude of the data. Due to the broad redshiftdistribution of galaxies at faint magnitude limits the correlation signal hasbeen extremely difficult to detect and interpret. We introduce a new techniquefor measuring the evolution of clustering. We utilize photometric redshifts,derived from multicolor surveys, to isolate redshift intervals and calculatethe evolution of the amplitude of the angular 2-pt correlation function.Applying these techniques to the the Hubble Deep Field we find that the shapeof the correlation function, at z=1, is consistent with a power law with aslope of -0.8. For z>0.4 the best fit to the data is given by a model ofclustering evolution with a comoving r0 = 2.37 Mpc and eps = -0.4 +/- 0.5,consistent with published measures of the clustering evolution. To match thecanonical value of r0 = 5.4 Mpc, found for the clustering of local galaxies,requires a value of eps = 2.10 +/- 0.5 (significantly more than linearevolution). The log likelihood of this latter fit is 4.15 less than that forthe r0 = 2.37 Mpc model. We, therefore, conclude that the parameterization ofthe clustering evolution of (1+z)^-(3+eps) is not a particularly good fit tothe data.Comment: 12 pages (3 figures). Accepted for publication in Ap