Recent stellar mass assembly of low-mass star-forming galaxies at redshifts 0.3 < z < 0.9

Abstract

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 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 ≤ log M∗/M⊙ ≤ 8.0), at 0.3 < zspec < 0.9, in the Extended-Chandra Deep Field-South field. Among them, 24 were selected with photometric stellarmass log M∗/M⊙ < 8.0, 0.3 < zphot < 1.0, and mNB816,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