The epoch when low-mass star forming galaxies ( LMSFGs ) form the bulk of their stellar mass is uncertain .
While some models predict an early formation , others favor a delayed scenario until later ages of the universe .
We present constraints on the star formation histories ( SFHs ) of a sample of LMSFGs obtained through the analysis of their spectral energy distributions ( SEDs ) using a novel approach that : ( 1 ) consistently combines photometric ( broadband ) and spectroscopic ( equivalent widths of emission lines ) data , and ( 2 ) uses physically motivated SFHs with non-uniform variations of the star formation rate ( SFR ) as a function of time .
The sample includes 31 spectroscopically confirmed LMSFGs ( 7.3 \leq log M _ { * } / M _ { \sun } \leq 8.0 ) , at 0.3 < z _ { \mathrm { spec } } < 0.9 , in the Extended-Chandra Deep Field-South field .
Among them , 24 were selected with photometric stellar mass log M _ { * } / M _ { \sun } < 8.0 , 0.3 < z _ { \mathrm { phot } } < 1.0 , and m _ { \mathrm { NB 816 ,AB } } < 26 mag ; the remaining 7 were selected as blue compact dwarfs within the same photometric redshift and magnitude ranges .
We also study a secondary sample of 43 more massive spectroscopically confirmed galaxies ( 8.0 < log M _ { * } / M _ { \sun } \leq 9.1 ) , selected with the same criteria .
The SFRs and stellar masses derived for both samples place our targets on the standard main sequence of star forming galaxies .
The median SFH of LMSFGs at intermediate redshifts appears to form 90 % of the median stellar mass inferred for the sample in the \sim 0.5–1.8 Gyr immediately preceding the observation .
These results suggest a recent stellar mass assembly for LMSFGs , consistent with the cosmological downsizing trends .
We find similar median SFH timescales for the more massive secondary sample .