  We have used integral field spectroscopy of a sample of six nearby
(z~0.01-0.04) high star-formation rate (SFR~10-40 solar masses per year)
galaxies to investigate the relationship between local velocity dispersion and
star formation rate on sub-galactic scales. The low redshift mitigates, to some
extent, the effect of beam smearing which artificially inflates the measured
dispersion as it combines regions with different line-of-sight velocities into
a single spatial pixel. We compare the parametric maps of the velocity
dispersion with the Halpha flux (a proxy for local star-formation rate), and
the velocity gradient (a proxy for the local effect of beam smearing). We find,
even for these very nearby galaxies, the Halpha velocity dispersion correlates
more strongly with velocity gradient than with Halpha flux - implying that beam
smearing is still having a significant effect on the velocity dispersion
measurements. We obtain a first-order non parametric correction for the
unweighted and flux weighted mean velocity dispersion by fitting a 2D linear
regression model to the spaxel-by-spaxel data where the velocity gradient and
the Halpha flux are the independent variables and the velocity dispersion is
the dependent variable; and then extrapolating to zero velocity gradient. The
corrected velocity dispersions are a factor of ~1.3-4.5 and ~1.3-2.7 lower than
the uncorrected flux-weighted and unweighted mean line-of-sight velocity
dispersion values, respectively. These corrections are larger than has been
previously cited using disc models of the velocity and velocity dispersion
field to correct for beam smearing. The corrected flux-weighted velocity
dispersion values are sigma_m~20-50 km/s.

Astrophysics of Galaxies