Star Formation in the Local Universe from the CALIFA sample. I.
  Calibrating the SFR using IFS data
  The Star Formation Rate (SFR) is one of the main parameters used to analyze
the evolution of galaxies through time. The need for recovering the light
reprocessed by dust commonly requires the use of low spatial resolution
far-infrared data. Recombination-line luminosities provide an alternative,
although uncertain dust-extinction corrections based on narrow-band imaging or
long-slit spectroscopy have traditionally posed a limit to their applicability.
Integral Field Spectroscopy (IFS) is clearly the way to overcome such
limitation. We obtain integrated H{\alpha}, ultraviolet (UV) and infrared
(IR)-based SFR measurements for 272 galaxies from the CALIFA survey at 0.005 <
z < 0.03 using single-band and hybrid tracers. We provide updated calibrations,
both global and split by properties (including stellar mass and morphological
type), referred to H{\alpha}. The extinction-corrected H{\alpha} luminosity
agrees with the updated hybrid SFR estimators based on either UV or H{\alpha}
plus IR luminosity over the full range of SFRs (0.03-20 M$_{\odot}$ yr$^{-1}$).
The coefficient that weights the amount of energy produced by newly-born stars
that is reprocessed by dust on the hybrid tracers, a$_{IR}$, shows a large
dispersion. However, it does not became increasingly small at high
attenuations, as expected if significant highly-obscured H$\alpha$ emission
would be missed. Lenticulars, early-type spirals and type-2 AGN host galaxies
show smaller coefficients due to the contribution of optical photons and AGN to
dust heating. In the Local Universe the H{\alpha} luminosity derived from IFS
observations can be used to measure SFR, at least in statistically-significant,
optically-selected galaxy samples. The analysis of the SFR calibrations by
galaxies properties could be potentially used by other works to study the
impact of different selection criteria in the SFR values derived.
