2016A&A...586A..83P

We combined the spectroscopic information from the 3D-HST survey with Herschel data to characterize the Hα dust attenuation properties of a sample of 79 main sequence star-forming galaxies at z ∼1 in the GOODS-S field. The sample was selected in the far-IR at λ=100 and/or 160µm and only includes galaxies with a secure Hα detection (S/N>3). From the low resolution 3D-HST spectra we measured the redshifts and the Hα fluxes for the whole sample. (A factor of 1/1.2 was applied to the observed fluxes to remove the [NII] contamination.) The stellar masses (M_*), infrared (L_IR), and UV luminosities (L_UV) were derived from the spectral energy distributions by fitting multiband data from GALEX near-UV to SPIRE 500µm. We estimated the continuum extinction E_star(B-V) from both the IRX=L_IR/L_UV ratio and the UV-slope, β, and found excellent agreement between the two. The nebular extinction was estimated from comparison of the observed SFR_Hα and SFR_UV. We obtained f=E_star(B-V)/E_neb(B-V)=0.93±0.06, which is higher than the canonical value of f=0.44 measured in the local Universe. Our derived dust correction produces good agreement between the Hα and IR+UV SFRs for galaxies with SFR≳20M_☉/yr and M_*≳5x10¹⁰ M_☉, while objects with lower SFR and M_* seem to require a smaller f-factor (i.e. higher Hα extinction correction). Our results then imply that the nebular extinction for our sample is comparable to extinction in the optical-UV continuum and suggest that the f-factor is a function of both M_* and SFR, in agreement with previous studies.