The Clustering of Faint Galaxies on Small Angular Scales

Abstract

We present a preliminary measurement of the angular clustering of faint ($R \le 25$) field galaxies in which we concentrate on the behavior of $w(θ)$ on small angular scales ($θ\ls 10''$). The galaxies are strongly clustered and $w(θ)$ is well-characterized by a power law of the form $A_w θ^{-δ}$. The best-fitting value of the power law index, $δ$, is, however, steeper than the fiducial value of $δ= 0.8$, indicating there are more pairs of galaxies separated by $θ\ls 10''$ in our sample than would be otherwise expected. Using the best-fitting form of $w(θ)$, we estimate that $\sim 10%$ of the galaxies are in physically close pairs (separations $\ls 21 h^{-1}$ kpc). This is a factor of order 2 larger than local galaxy samples, but comparable to galaxy samples with $ \sim 0.4$. The mean redshift of our galaxies is of order 0.95, and, therefore, our result suggests that there was little or no evolution in the merger rate of galaxies between $z \sim 1$ and $z \sim 0.4$.