| Abstract |
We used the GALEX data archive of a sample of 12 luminous & ultraluminous in-
frared galaxies, (U)LIRGs, from the Great Observatories All-Sky Survey (GOALS).
UV photometry of these galaxies has been performed to measure the flux densities
in the FUV and NUV bands. We also performed the aperture correction photome-
try of the 3 ULIRGs. Combining our UV measurements with the IR luminosities of
Armus et al. (2009) of these galaxies we confirm the following: (U)LIRGs have large
infrared excess (IRX) compared to normal starburst galaxies. In general, more lu-
minous (U)LIRGs have larger IRX. The LIR for (U)LIRGs would be underestimated if we tried to measure it using UV measurements and the starburst relation (SR) of Meurer et al. (1999). The deviation above the starburst relation, defined as ΔIRX, increases as LIR increases implying that the decoupling between IR and UV emission becomes greater from LIRGs to ULIRGs. We also examined the star formation rate (SFR) of these galaxies. In particular, the SFR is calculated from the FUV emission and we found that it is only a small fraction, (on average 1.7%), of that obtained from the IR measurements. In order to take into account the extinction that is affecting the UV emission of galaxies we corrected the FUN flux densities for obscuration using two methods: those of Buat (2005) and β(GALEX) slope. Once corrected, the SFR derived accounts for 50.54% and 24.37% of the SFRIR, respectively. We also found
that the extinction correction from Buat (2005) is more reliable to (U)LIRGs than the
correction with β(GALEX). Finally, the ratio of SFR IR / SFRUVdustcorrected increases as the LIR increases for (U)LIRGs. Therefore, the SFR of (U)LIRGs based on UV measurements
underestimate their true SFR.
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UV and IR properties of luminous infrared galaxies (LIRGs)
