Ultraviolet-to-far-infrared properties of local star-forming galaxies

We present the results of a multiwavelength study of nearby galaxies aimed at understanding the relation between the ultraviolet and far-infrared emission in star-forming galaxies. The data set comprises new ultraviolet (from HST STIS), ground-based H alpha, and radio continuum observations, together with archival infrared data (from IRAS and ISO). The local galaxies are used as benchmarks for comparison of the infrared-to-ultraviolet properties with two populations of high-redshift galaxies: the submillimeter star-forming galaxies detected by SCUBA and the ultraviolet-selected Lyman break galaxies (LBGs). In addition, the longwavelength baseline covered by the present data enables us to compare the star formation rates (SFRs) derived from the observed ultraviolet, H alpha, infrared, and radio luminosities and to gauge the impact of dust opacity in the local galaxies. We also derive a new calibration for the nonthermal part of the radio SFR estimator, based on the comparison of 1.4 GHz measurements with a new estimator of the bolometric luminosity of the star-forming regions. We find that more actively star-forming galaxies show higher dust opacities, which is in line with previous results. We find that the local star-forming galaxies have a lower F-lambda(205 mu m)/F-lambda(UV) ratio by 2 - 3 orders of magnitude than the submillimeter-selected galaxies and may have a similar or somewhat higher F-lambda(205 mu m)/F-lambda(UV) ratio than LBGs. The F lambda(205 mu m)/F-lambda(UV) ratio of the local galaxy population may be influenced by the cool dust emission in the far-infrared heated by nonionizing stellar populations, which may be reduced or absent in the LBGs.