Strong Clustering of Faint Galaxies at Small Angular Scales

The 2-point angular correlation function of galaxies, ω(θ) , has been computed on equatorial fields observed with the CTIO 4m prime focus, within a total area of 2.31 deg. In the magnitude range 19 ≤ mR ≤ 21.5, corresponding to < z >≈ 0.35, we find an excess of power in ω(θ) at scales 2 ≤ θ ≤ 6 over what would be expected from an extrapolation of ω(θ) measured at larger θ. The significance of this excess is ≈ 5σ. At larger scales, 6 < θ ≤ 24, the amplitude of ω(θ) is 1.6 times smaller than the standard no evolutionary model. At these scales there is remarkable agreement between the present data and Infante & Pritchet (1995). At large angular scales (6 < θ ≤ 24) the data is best described by a model where clustering evolution in ξ(r, z) has taken place. Strong luminosity evolution cannot be ruled out with the present data. At smaller scales, 2 ≤ θ ≤ 6, our data are formally fit by models where ǫ = −2.4(Ω = 0.2, ro = 5.1hMpc) or ro = 7.3hMpc (Ω = 0.2, ǫ = 0). If the mean redshift of our sample is 0.35 then our data show a clear detection of the scale (≈ 19hkpc) where the clustering evolution approaches a highly non linear regime, i.e., ǫ ≤ 0. The rate at which galaxies merge has been computed. If this rate is proportional to (1 + z), then m = 2.2± 0.5. Subject headings: galaxies: evolution – galaxies:formation – galaxies:interactions