Abstract

We present new results from a multi-wavelength analysis of normal/typical star-forming (SF) galaxies combining a sample of strongly lensed galaxies at z_{1.5-4 and z}6-7, a large sample of LBGs from z_{3-8, and a Herschel-selected sample at z}1.5-3. The observations include deep ground-based, HST , Spitzer, and Herschel imaging, plus LABOCA /SCUBA2 data, IRAM and ALMA dust continuum observations for some of the objects. The observed SEDs are modelled with our SED fitting tool including nebular emission for the stellar part, and allowing for energy-conserving global SED fits including also dust emission. We obtain direct constraints on dust attenuation from IR and UV measurements, yielding new information on the dependence of attenuation on galaxy mass and on its redshift evolution. Both the empirical data and our modelling shows that the UV attenuation at z>3 may be larger than commonly thought, with implications on the global history of star formation (SFR density) at high redshift. We also present evidence for variable star formation histories in high-z galaxies and discuss important implications on the specific SFT , its redshift evolution, the SF main sequence at high redshift, and other related issues.