Beyond the fibre: Resolved properties of SDSS galaxies
  We have used the VIMOS integral field spectrograph to map the emission line
properties in a sample of 24 star forming galaxies selected from the SDSS
database. In this data paper we present and describe the sample, and explore
some basic properties of SDSS galaxies with resolved emission line fields. We
fit the Halpha+[NII] emission lines in each spectrum to derive maps of
continuum, Halpha flux, velocity and velocity dispersion. The Halpha, Hbeta,
[NII] and [OIII] emission lines are also fit in summed spectra for circular
annuli of increasing radius. A simple mass model is used to estimate dynamical
mass within 10 kpc, which compared to estimates of stellar mass shows that
between 10 and 100% of total mass is in stars. We present plots showing the
radial behaviour of EW[Halpha], u-i colour and emission line ratios. Although
EW[Halpha] and u-i colour trace current or recent star formation, the radial
profiles are often quite different. Whilst line ratios do vary with annular
radius, radial gradients in galaxies with central line ratios typical of AGN or
LINERS are mild, with a hard component of ionization required out to large
radii. We use our VIMOS maps to quantify the fraction of Halpha emission
contained within the SDSS fibre, taking the ratio of total Halpha flux to that
of a simulated SDSS fibre. A comparison of the flux ratios to colour-based SDSS
extrapolations shows a 175% dispersion in the ratio of estimated to actual
corrections in normal star forming galaxies, with larger errors in galaxies
containing AGN. We find a strong correlation between indicators of nuclear
activity: galaxies with AGN-like line ratios and/or radio emission frequently
show enhanced dispersion peaks in their cores, requiring non-thermal sources of
heating. Altogether, about half of the galaxies in our sample show no evidence
for nuclear activity or non-thermal heating.
