A targeted survey for HI clouds in galaxy groups

Five galaxy groups with properties similar to those of the Local Group have been surveyed for H I clouds with the Arecibo Telescope. In total 300 poin tings have been observed on grids of approximately 2.5 x 1.5 Mpc(2) centred on the groups. The 4.5 sigma detection limit on the minimal detectable H I masses is approximately 7 x 10(6) M-circle dot (H-0 = 65 km s(-1) Mpc(-1)) . All detections could be attributed to optical galaxies; no significant de tections of H I clouds have been made. This null result leads to the conclu sion that the total H I mass of intragroup clouds must be less than 10 per cent of the total H I mass of galaxy groups and less than 0.05 per cent of the dynamical mass. The recent hypothesis that Galactic high-velocity cloud s are Local Group satellite galaxies is highly inconsistent with these obse rvations.