To understand how strong emission line galaxies ( ELGs ) contribute to the overall growth of galaxies and star formation history of the universe , we target Strong ELGs ( SELGs ) from the ZFOURGE imaging survey that have blended H \beta + [ O iii ] rest-frame equivalent widths of > 230 Å and 2.5 < z _ { phot } < 4.0 .
Using Keck/MOSFIRE , we measure 49 redshifts for galaxies brighter than K _ { s } = 25 mag as part of our Multi-Object Spectroscopic Emission Line ( MOSEL ) survey .
Our spectroscopic success rate is \sim 53 % and z _ { phot } uncertainty is \sigma _ { z } = [ \Delta z / ( 1 + z ) ] = 0.0135 .
We confirm 31 ELGs at 3 < z _ { spec } < 3.8 and show that Strong ELGs have spectroscopic rest-frame [ O iii ] 5007Å equivalent widths of 100 - 500 Å and tend to be lower mass systems [ \log ( { M } _ { \star } / { M } _ { \odot } ) \sim 8.2 - 9.6 ] compared to more typical star-forming galaxies .
The Strong ELGs lie \sim 0.9 dex above the star-forming main-sequence at z \sim 3.5 and have high inferred gas fractions of { f } _ { gas } \gtrsim 60 % , i.e .
the inferred gas masses can easily fuel a starburst to double stellar masses within \sim 10 - 100 Myr .
Combined with recent results using ZFOURGE , our analysis indicates that 1 ) strong [ O iii ] 5007Å emission signals an early episode of intense stellar growth in low mass [ M _ { \star } < 0.1 M ^ { \star } ] galaxies and 2 ) many , if not most , galaxies at z > 3 go through this starburst phase .
If true , low-mass galaxies with strong [ O iii ] 5007Å emission ( EW _ { rest } > 200 Å ) may be an increasingly important source of ionizing UV radiation at z > 3 .