GMRT HI observations of the Eridanus group of galaxies

Abstract

The GMRT HI 21cm-line observations of galaxies in the Eridanus group are presented. The Eridanus group, at a distance of ~23 Mpc, is a loose group of ~200 galaxies. The group extends to more than 10 Mpc in projection. The velocity dispersion of the galaxies in the group is ~240 km s-1. The galaxies are clustered into different sub-groups. The overall population mix of the group is 30% (E + S0) and 70% (Sp + Irr). The observations of 57 Eridanus galaxies were carried out with the GMRT for ~ 200 h. HI emission was detected from 31 galaxies. The channel rms of ~1 mJy beam-1 was achieved for most of the image-cubes made with 4 h of data. The corresponding HI column density sensitivity (3σ) is ~1 × 1020 cm-2 for a velocity-width of ~ 13.4 km s-1. The 3σ detection lss surface densities, HI disk parameters and HI rotation curves are presented. The velocity fields are analysed separately for the approaching and the receding sides of the galaxies. These data will be used to study the HI and the radio continuum properties, the Tully-Fisher relations, the dark matter halos, and the kinematical and HI lopsidedness in galaxies.