Local Structures as revealed by HIPASS

Abstract

The HI Parkes All-Sky Survey (HIPASS) gives an unprecedented view of the local large-scale structures in the southern sky. I will review the results from the HIPASS Bright Galaxy Catalog (BGC, Koribalski et al. 2004) and the first version of the deep catalog (HICAT, Meyer et al. 2004) with particular emphasis on galaxy structures across the Zone of Avoidance. Some previously hardly noticed galaxy groups stand out quite distinctively in the HI sky distribution and several large-scale structures are seen for the first time. Because HI surveys preferentially detect late-type spiral and dwarf galaxies, their distribution is less clustered than that of optically selected galaxies. HI surveys also significantly enhance the connectivity of large-scale filaments by filling in gaps populated by gas-rich galaxies.