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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 Hα, 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 Hα. The extinction-corrected Hα luminosity agrees with the updated hybrid SFR estimators based on either UV or Hα 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$α$ 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 Hα 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.