HI Observations of two New Dwarf Galaxies: Pisces A & B with the SKA
  Pathfinder KAT-7
  Context. Pisces A & Pisces B are the only two galaxies found via optical
imaging and spectroscopy out of 22 HI clouds identified in the GALFAHI survey
as dwarf galaxy candidates. Aims. Derive the HI content and kinematics of
Pisces A & B. Methods. Aperture synthesis HI observations using the seven dish
Karoo Array Telescope (KAT-7), which is a pathfinder instrument for MeerKAT,
the South African precursor to the mid-frequency Square Kilometre Array
(SKA-MID). Results. The small rotation velocities detected of ~5 km/sec and ~10
km/sec in Pisces A & B respectively, and their HI content show that they are
really dwarf irregular galaxies (dIrr). Despite that small rotation component,
it is more the random motions ~9-11 km/sec that provide most of the
gravitational support, especially in the outer parts. The study of their
kinematics, especially the strong gradients of random motions, suggest that
those two dwarf galaxies are not yet in equilibrium. Conclusions. These HI rich
galaxies may be indicative of a large population of dwarfs at the limit of
detectability. However, such gas-rich dwarf galaxies will most likely never be
within the virial radius of MW-type galaxies and become sub-halo candidates.
Systems such as Pisces A & B are more likely to be found at a few Mpc.s from
MW-type galaxies.
