Ultraviolet–to–Far‐Infrared Properties of Local Star‐forming Galaxies

We present the results of a multiwavelength study of nearby galaxies, aimedat understanding the relation between the ultraviolet and far-infrared emissionin star-forming galaxies. The dataset comprises new ultraviolet (fromHST/STIS), ground-based Halpha, and radio continuum observations, together witharchival infrared data (from IRAS and ISO). The local galaxies are used asbenchmarks for comparison of the infrared-to-ultraviolet properties with twopopulations of high-redshift galaxies: the sub-millimeter star-forming galaxiesdetected by SCUBA and the ultraviolet-selected Lyman Break galaxies. Inaddition, the long wavelength baseline covered by the present data enables usto compare the star formation rates (SFRs) derived from the observedultraviolet, Halpha, infrared, and radio luminosities, and to gauge the impactof dust opacity in the local galaxies. We also derive a new calibration for thenon-thermal part of the radio SFR estimator, based on the comparison of 1.4 GHzmeasurements with a new estimator of the bolometric luminosity of the starforming regions. We find that more actively star forming galaxies show higherdust opacities, in line with previous results. We find that the localstar-forming galaxies have lower F(205um)/F(UV) ratio, by two-three orders ofmagnitude than the submillimeter-selected galaxies, and may have similar orsomewhat higher F(205um)/F(UV) than Lyman Break Galaxies. The F(205um)/F(UV)ratio of the local galaxy population may be influenced by the cool dustemission in the far-infrared heated by non-ionizing stellar populations, whichmay be reduced or absent in the LBGs.Comment: 34 pages, 9 figures, to appear in the 20 May 2005 Ap