The Califa and Hipass velocity function for all morphological galaxy
  types
  The velocity function is a fundamental observable statistic of the galaxy
population, similarly impor- tant as the luminosity function, but much more
difficult to measure. In this work we present the first directly measured
circular velocity function that is representative between 60 < v_circ < 320
km/s for galaxies of all morphological types at a given rotation velocity. For
the low mass galaxy population (60 < v_circ < 170 km/s), we use the HIPASS
velocity function. For the massive galaxy population (170 < v_circ < 320 km/s),
we use stellar circular velocities from the Calar Alto Legacy Integral Field
Area Survey (CALIFA). In earlier work we obtained the measurements of circular
velocity at the 80% light radius for 226 galaxies and demonstrated that the
CALIFA sample can produce volume- corrected galaxy distribution functions. The
CALIFA velocity function includes homogeneous velocity measurements of both
late and early-type rotation-supported galaxies and has the crucial advantage
of not missing gas-poor massive ellipticals that HI surveys are blind to. We
show that both velocity functions can be combined in a seamless manner, as
their ranges of validity overlap. The resulting observed velocity function is
compared to velocity functions derived from cosmological simulations of the z =
0 galaxy population. We find that dark matter-only simulations show a strong
mismatch with the observed VF. Hydrodynamic simulations fare better, but still
do not fully reproduce observations.
