that of normal star-forming galaxies in the local Universe. On the other hand, follow-up of bright submillimeter galaxies (SMGs) revealed that their very intense SFR ($\sim$1000M$_\odot$/yr) is also driven by a SFE boosted by a factor of 10 with respect to normal star-forming galaxies in the local Universe [e.g., @Greve2005; @Frayer2008; @Daddi2009a; @Daddi2009b], likely induced by a major merger. This difference can be understood if we consider that galaxies are driven by two types of star formation activity: smooth processes fed by large reservoirs of gas in normal star-forming galaxies and boosted star-formation in gas rich mergers [@Daddi2010b; @Genzel2010].\
Using models based on the existence of this main-sequence of star-forming galaxies, i.e., a tight correlation between SFR and stellar mass, and outliers of this sequence with boosted sSFRs (SFR/M$_\star$) called starbursts hereafter, @Sargent2012 showed that the galaxies with the highest SFR mainly correspond to starbursts, while the bulk of the star formation budget ($\sim$85%) is hosted in normal star-forming galaxies. This approach allows us to better understand the heterogeneous characteristic of distant objects concerning their gas fraction and their SFE [@Sargent2014]. The quick rise of the sSFR would thus be explained by larger gas reservoirs in main-sequence galaxies. However, the 