2-point Correlation Function of HI-selected Galaxies

The 2-point spatial correlation function (CF), $\xi(s)$, has been used to study the clustering of the galaxies in the preliminary version of the HIPASS Bright Galaxy Catalogue (HIPASS BGC), which includes the 1,000 HI brightest galaxies in the Southern sky. This is the first time the CF has been used to analyse an HI-selected sample. The CF is well described by a power law, $\xi(s)\sim(s/s_0)^{-\gamma}$, with slope $\gamma\sim1.7$ and correlation length $s_0\sim3.55$ $h^{-1}$ Mpc using Peebles estimator. However, when the Hamilton estimator is used, the CF is fit with $\gamma\sim2.19$ and $s_0\sim3.37$ $h^{-1}$ Mpc. Note that, these HI-selected galaxies show less clustering than optically-selected surveys which have a correlation length $s_0\sim$ 5.5 $h^{-1}$ Mpc or larger.