A spectroscopic measure of the star formation rate density in dwarf galaxies at z ~ 1

Abstract

We use a K-selected (22.5 < KAB < 24.0) sample of dwarf galaxies (8.4 < 10) at 0.89 < z < 1.15 in the Chandra Deep Field-South to measure their contribution to the global star formation rate density (SFRD), as inferred from their [O II] flux. By comparing with [O II ]-based studies of higher stellar mass galaxies, we robustly measure a turnover in the [O II] luminosity density at a stellar mass of M ~ 1010 M⊙. By comparison with the [O II]-based SFRD measured from the Sloan Digital Sky Survey we confirm that, while the SFRD of the lowest mass galaxies changes very little with time, the SFRD of more massive galaxies evolves strongly, such that they dominate the SFRD at z = 1. © 2009 The Authors. Journal compilation © 2009 RAS.