Dust attenuation in z $\sim$ 1 galaxies from Herschel and 3D-HST H$\hat{I}\pm$ measurements

Abstract

We combined the spectroscopic information from the 3D-HST survey with \textit{Herschel} data to characterize the H$\hat{I}\pm$ dust attenuation properties of a sample of 79 main sequence star-forming galaxies at $z\sim 1$ in the GOODS-S field. The sample was selected in the far-IR, at $\hat{I}»$=100 and/or 160 $\hat{I}¼$m, and only includes galaxies with a secure H$\hat{I}\pm$ detection (S/N$>$3). From the low resolution 3D-HST spectra we measured the redshifts and the H$\hat{I}\pm$ 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${}_{\star }$), infrared (L${}_{IR}$) and UV luminosities (L${}_{UV}$) were derived from the SEDs by fitting multi-band data from GALEX near-UV to SPIRE 500 $\hat{I}¼$m. We estimated the continuum extinction E${}_{star}$(B-V) from both the IRX=L${}_{IR}$/L${}_{UV}$ ratio and the UV-slope, ${\hat{I}}^2$, and found an excellent agreement between the two. The nebular extinction was estimated from comparison of the observed SFR${}_{H\hat{I}\pm }$ and SFR${}_{UV}$. We obtained \emph{f}=E${}_{star}$(B-V)/E${}_{neb}$(B-V)=0.93$\pm$0.06, i.e. higher than the canonical value of \emph{f}=0.44 measured in the local Universe. Our derived dust correction produces good agreement between the H$\hat{I}\pm$ and IR+UV SFRs for galaxies with SFR$\gtrsim$ 20 M${}_{\odot }$/yr and M${}_{\star }\gtrsim 5\times 10^{10}$ M${}_{\odot }$, while objects with lower SFR and M${}_{\star }$ seem to require a smaller \emph{f}-factor (i.e. higher H$\hat{I}\pm$ extinction correction). Our results then imply that the nebular extinction for our sample is comparable to that in the optical-UV continuum and suggest that the \emph{f}-factor is a function of both M${}_{\star }$ and SFR, in agreement with previous studies.

19 pages, 17 figures. Accepted for publication in A&A