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

TL;DR

This study measures the contribution of dwarf galaxies at z~1 to the overall star-formation rate density using spectroscopic data, revealing a turnover in luminosity density at a specific stellar mass and contrasting the evolution of low- and high-mass galaxy SFRDs.

Contribution

It provides the first robust measurement of the star-formation rate density contribution from dwarf galaxies at z~1 using [OII] flux, highlighting a turnover in luminosity density at M~10^10 Msun.

Findings

SFRD of low-mass galaxies remains nearly constant from z~1 to present.

SFRD of higher-mass galaxies increases significantly towards z~1.

A turnover in [OII] luminosity density occurs at M~10^10 Msun.

Abstract

We use a K-selected (22.5 < K_AB < 24.0) sample of dwarf galaxies (8.4 < log(M*/Msun) < 10) at 0.89<z<1.15 in the Chandra Deep Field South (CDFS) to measure their contribution to the global star-formation rate density (SFRD), as inferred from their [OII] flux. By comparing with [OII]-based studies of higher stellar mass galaxies, we robustly measure a turnover in the [OII] luminosity density at a stellar mass of M~10^10 Msun. By comparison with the [OII]-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.