Clustering of HI galaxies in the HI parkes all sky survey and arecibo legacy fast alfa survey

Abstract

We investigate the clustering of H I-selected galaxies in the Arecibo Legacy Fast ALFA Survey (ALFALFA) and compare results with those obtained for the H I Parkes All Sky Survey (HIPASS). Measurements of the angular correlation function and the inferred 3D clustering are compared with results from direct spatial-correlation measurements. We are able to measure clustering on smaller angular scales and for galaxies with lower H I masses than was previously possible. We calculate the expected clustering of dark matter using the redshift distributions of the HIPASS and ALFALFA, and show that the ALFALFA sample is somewhat more antibiased with respect to dark matter than the HIPASS sample.