SHARDS: A global view of the star formation activity at z~0.84 and z~1.23

Antonio Cava, Pablo G. Perez-Gonzalez, M. Carmen Eliche-Moral, Elena Ricciardelli, Alba Vidal-Garcia, Belen Alcalde-Pampliega, Almudena Alonso-Herrero, Guillermo Barro, Nicolas Cardiel, A. Javier Cenarro, Stephane Charlot, Emanuele Daddi, Miroslava Dessauges-Zavatsky, Helena Dominguez Sanchez, Nestor Espino-Briones, Pilar Esquej, Jesus Gallego, Antonio Hernan-Caballero, Marc Huertas-Company, Casiana Munoz-Tunon, Jose M. Rodriguez-Espinosa, Lucia Rodriguez-Munoz, Daniel Schaerer, Laurence Tresse, Victor Villar

Published 2015-07-28Version 1

In this paper, we present a comprehensive analysis of star-forming galaxies (SFGs) at intermediate redshifts (z~1). We combine the ultra-deep optical spectro-photometric data from the SHARDS survey with deep UV-to-FIR observations in the GOODS-N field to build and characterize a complete sample of SFGs at z~0.84 and z~1.23. Exploiting two of the 25 SHARDS medium-band filters, F687W17 and F823W17, we select [OII] emission line galaxies (ELGs) at z~0.84 and z~1.23 and characterize their physical properties. Their rest-frame equivalent widths (EWrf([OII])), line fluxes, luminosities, star formation rates (SFRs) and dust attenuation properties are investigated. The evolution of the EWrf([OII]) closely follows the SFR density evolution of the Universe, with a EWrf([OII])$\propto$(1+z)$^3$ trend up to redshift z~1, followed by a possible flattening. The SF properties of the galaxies selected on the basis of their [OII] emission are compared with complementary samples of SFGs selected by their MIR and FIR emission, and also with a general mass-selected sample of galaxies at the same redshifts. We observationally demonstrate that the UVJ diagram (or, similarly, a cut in the specific SFR) is only partially able to distinguish the quiescent galaxies from the SFGs. The SFR-M$_*$ relation is investigated for the different samples, finding a logarithmic slope ~1, in good agreement with previous results. The dust attenuations derived from different SFR indicators (UV(1600), UV(2800), [OII], IR) are compared, finding clear trends with respect to both the stellar mass and total SFR, with more massive and highly star-forming galaxies being affected by stronger dust attenuation. The full SHARDS dataset allows the extension of this study to other redshifts and emission lines, thus providing a powerful tool for the study of ELGs up to high redshifts. (Abridged)