DUST-CORRECTED STAR FORMATION RATES OF GALAXIES. II. COMBINATIONS OF ULTRAVIOLET AND INFRARED TRACERS

Abstract

We present new calibrations of far-ultraviolet (FUV) attenuation as derived\nfrom the total infrared to FUV luminosity ratio (IRX) and the FUV-NUV color. We\nfind that the IRX-corrected FUV luminosities are tightly and linearly\ncorrelated with the attenuation-corrected H\\alpha\\ luminosities (as measured\nfrom the Balmer decrement), with a rms scatter of $\\pm 0.09$ dex. The ratios of\nthese attenuation-corrected FUV to H\\alpha\\ luminosities are consistent with\nevolutionary synthesis model predictions, assuming a constant star formation\nrate over 100 Myr, solar metallicity and either a Salpeter or a Kroupa IMF with\nlower and upper mass limits of 0.1 and 100\\msun. The IRX-corrected FUV to\nBalmer-corrected H\\alpha\\ luminosity ratios do not show any trend with other\ngalactic properties over the ranges covered by our sample objects. In contrast,\nFUV attenuation derived from the FUV-NUV color (UV spectral slope) show much\nlarger random and systematic uncertainties. When compared to either\nBalmer-corrected H\\alpha\\ luminosities or IRX-corrected FUV luminosities the\ncolor-corrected FUV luminosities show $\\sim 2.5$ times larger rms scatter, and\nsystematic nonlinear deviations as functions of luminosity and other\nparameters. Linear combinations of 25um and 1.4GHz radio continuum luminosities\nwith the observed FUV luminosities are also well correlated with the\nBalmer-corrected H\\alpha\\ luminosities. These results provide useful\nprescriptions for deriving attenuation-corrected star formation rates of\ngalaxies based on linear combinations of UV and IR or radio luminosities, which\nare presented in convenient tabular form. Comparisons of our calibrations with\nattenuation corrections in the literature and with dust attenuation laws are\nalso made.\n