Kinematics of giant low surface brightness galaxies

High sensitivity H I observations now exist for six giant low surface brightness (LSB) disk galaxies including the two prototypes, Malin 1 (Bothun et al. 1987; Impey & Bothun 1989) and F568-6 (also known as Malin 2; Bothun et al. 1990). Their H I surface brightnesses are generally low, but proportionally not as low as their optical surface brightnesses. Their total H I masses and radial extents are quite large, however, with M-HI similar to 10(10)M(.)h(75)(-2) and with detectable H I out to 100 kpc h(75)(-1) or more in a couple of cases. The rotation curves of these systems rise slowly and are consistent with negligible disk contribution, similar to many previously observed dwarf galaxies. However, the peak rotation velocities of these galaxies are high (>200 km s(-1)) and infer high dynamical masses. These galaxies provide the some of the first examples of galaxies that are both massive and dark matter dominated