Molecular content of polar-ring galaxies
  We have searched for CO lines in a sample of 21 new morphologically
determined polar-ring galaxies (of which nine are kinematically confirmed),
obtained from a wide search in the Galaxy Zoo project by Moiseev and
collaborators. Polar-ring galaxies (PRG) are a unique class of objects, tracing
special episodes in the galaxy mass assembly: they can be formed through galaxy
interaction and merging, but also through accretion from cosmic filaments.
Furthermore, they enable the study of dark matter haloes in three dimensions.
The polar ring itself is a sub-system rich in gas, where molecular gas is
expected, and new stars are formed. Among the sample of 21 PRG, we have
detected five CO-rich systems, that can now be followed up with higher spatial
resolution. Their average molecular mass is 9.4 10**9 Mo, and their average gas
fraction is 27% of their baryonic mass, with a range from 15 to 43%, implying
that they just accreted a large amount of gas. The position of the detected
objects in the velocity-magnitude diagram is offset from the Tully-Fisher
relation of normal spirals, as was already found for PRGs. This work is part of
our multi-wavelength project to determine the detailed morphology and dynamics
of polar-ring galaxies, test through numerical models their formation scenario,
and deduce their dark matter content and 3D-shape.
