Oxford University Press (OUP), Monthly Notices of the Royal Astronomical Society, 4(416), p. 2712-2724
DOI: 10.1111/j.1365-2966.2011.19223.x
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We present a calibration of the star formation rate (SFR) as a function of the [C II] 157.74 mu m luminosity for a sample of 24 star-forming galaxies in the nearby universe. In order to calibrate the SFR against the line luminosity, we rely on both GALEX FUV data, which is an ideal tracer of the unobscured star formation, and Spitzer MIPS 24 mu m, to probe the dust-enshrouded fraction of star formation. For this sample of normal star-forming galaxies, the [C II] luminosity correlates well with the star formation rate. However, the extension of this relation to more quiescent (H alpha EW <= 10 angstrom) or ultra luminous galaxies (L-TIR >= 10(12) L-circle dot) should be handled with caution, since these objects show a non-linearity in the L-[C II]-to-L-FIR ratio as a function of L-FIR (and thus, their star formation activity). Two possible scenarios can be invoked to explain the tight correlation between the [C II] emission and the star formation activity on a global galaxy-scale. The first interpretation could be that the [C II] emission from photo dissociation regions arises from the immediate surroundings of actively star-forming regions and contributes a more or less constant fraction on a global galaxy-scale. Alternatively, we consider the possibility that the [C II] emission is associated to the cold interstellar medium, which advocates an indirect link with the star formation activity in a galaxy through the Schmidt law.