Dust attenuation in z ~ 1 galaxies from Herschel and 3D-HST Hα measurements

¹ Dipartimento di Fisica e AstronomiaUniversità di Padova, vicolo dell’Osservatorio 2, 35122 Padova, Italy
e-mail: annagrazia.puglisi@studenti.unipd.it
² Dipartimento di Fisica e Astronomia, Università di Bologna, via Ranzani 1, 40127 Bologna, Italy
³ INAF–Osservatorio Astronomico di Bologna, via Ranzani 1, 40127 Bologna, Italy
⁴ INAF–Osservatorio Astronomico di Padova, Vicolo dell’Osservatorio, 5, 35122 Padova, Italy
⁵ Institute for Astronomy, Departement of Physics, ETH Zurich, Wolfgang-Pauli-Strasse 27, 8093 Zurich, Switzerland
⁶ Max-Planck-Institut für extraterrestrische Physik, Giessenbachstrasse, 85748 Garching, Germany
⁷ Max-Planck-Institut für Extraterrestrische Physik (MPE), Postfach 1312, 85741 Garching, Germany
⁸ Laboratoire AIM-Paris-Saclay, CEA/DSM-CNRS-Université Paris Diderot, Irfu/Service d’Astrophysique, CEA Saclay, Orme des Merisiers, 91191 Gif sur Yvette, France
⁹ Astronomy Centre, Dept. of Physics & Astronomy, University of Sussex, Brighton BN1 9QH, UK
¹⁰ Kavli Institute for the Physics and Mathematics of the Universe, Todai Institute for Advanced Study, the University of Tokyo, 277-8583 Kashiwa, Japan

Received: 19 June 2015
Accepted: 28 November 2015

Abstract

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 160 μm 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 500 μm. 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_⋆ ≳ 5 × 10¹⁰M_⊙, 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.