Strong Clustering of Faint Galaxies at Small Angular Scales

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Abstract
The two-point angular correlation function of galaxies, ω(θ), has been computed on equatorial fields observed with the Cerro Telolo Inter-American Observatory 4 m prime focus, within a total area of 2.31 deg2. 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 ≈ 5 σ. At larger scales, 6'' < θ ≤ 24'', the amplitude of ω(θ) is 1.6 times smaller than the standard nonevolutionary 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 are 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 fitted by models where = -2.4(Ω = 0.2, r0 = 5.1 h-1 Mpc) or r0 = 7.3 h-1 Mpc (Ω = 0.2, = 0). If the mean redshift of our sample is 0.35, then our data show a clear detection of the scale (≈ 19 h-1 kpc) where the clustering evolution approaches a highly nonlinear regime, i.e., ≤ 0. The rate at which galaxies merge has been computed. If this rate is proportional to (1 + z)m, then m = 2.2 ± 0.5.
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