The OTELO survey: the star formation rate evolution of low-mass galaxies

TL;DR

This study analyzes low-mass emission line galaxies from the OTELO survey to understand their star formation rate evolution, revealing a flat trend in star formation activity and no significant change in galaxy number density up to redshift 1.4.

Contribution

It provides the lowest mass sample-based estimate of the specific star formation rate--stellar mass relation and shows no evolution in galaxy number density up to redshift 1.4.

Findings

Flat star formation rate density with redshift.

No significant change in galaxy number density up to z~1.4.

Gradual shift in star formation processes from high-mass to low-mass galaxies.

Abstract

We present the analysis of a sample of \ha\,, \hb\ and \oii\ emission line galaxies from the \otelo\ survey, with masses typically below $log(M_*/M_\sun) \sim 9.4$ and redshifts between $z \sim 0.4$ and 1.43. We study the star formation rate, star formation rate density, and number density and their evolution with redshift. We obtain a robust estimate of the specific star formation rate -- stellar mass relation based on the lowest mass sample published so far. We also determine a flat trend of the star formation rate density and number density with redshift. Our results suggest a scenario of no evolution of the number density of galaxies, regardless of their masses, up to redshift $z\sim1.4$. This implies a gradual change of the relative importance of the star forming processes, from high-mass galaxies to low-mass galaxies, with decreasing redshift. We also find little or no variation of the star formation rate density in the redshift range of $0.4<z<1.43$.