Galaxy clustering in the Herschel deep field

Abstract

(abridged) We present a study of the angular correlation function as measured in the William Herschel Deep Field. This field covers 50 arcmin$^2$ and with it we are able to investigate the scaling of the angular correlation function to $B\sim28$, $R, I\sim 26$,$K\sim20$ and $H\sim22.5$. We compare our measurements to results obtained from the smaller Hubble Deep Field. To interpret our results, we use a model which correctly predicts colours, number counts and redshift distributions for the faint galaxy population. We find that at fixed separation the amplitude of $ω(θ)$ measured in $BRI$ bandpasses is lower than the predictions of a model containing with no luminosity evolution and stable clustering growth in proper co-ordinates. However, in the near-infrared bandpasses, our measurements are consistent with the predictions of an essentially non-evolving $K-$ selected galaxy redshift distribution. In the range $B\sim27-28$ we find that our correlation amplitudes are independent of magnitude, which is consistent with the observed flattening of the number count slope and correspondingly slower increase of the cosmological volume element expected at these magnitudes. Our measurements in all bandpasses are consistent with a rapid growth of galaxy clustering ($0 < ε< 2 $ in the normal parametrisation) on the sub-Mpc scales which our survey probes. We demonstrate that this rapid growth of clustering is consistent with the predictions of biased models of galaxy formation, which indicate that a rapid rate of clustering growth is expected for the intrinsically faint galaxies which dominate our survey.