Evolution of the star formation histories of BLAST galaxies

TL;DR

This study reconstructs star formation histories of BLAST galaxies, revealing mass-dependent differences and evolution patterns consistent with galaxy downsizing, using multi-wavelength photometry and a novel SFH reconstruction method.

Contribution

It applies a new SFH reconstruction technique to BLAST galaxies, demonstrating mass-dependent star formation patterns and evolution.

Findings

Low mass galaxies have late star formation bursts.

High mass galaxies formed most of their stars earlier.

High mass SFHs evolve more strongly over time.

Abstract

We have measured star formation histories (SFHs) and stellar masses of galaxies detected by the Balloon-borne Large Aperture Sub-millimetre Telescope (BLAST) over approximately 9 square degrees centred on the Chandra Deep Field South. We have applied the recently developed SFH reconstruction method of Dye et al. to optical, near-infrared and mid-infrared photometry of 92 BLAST galaxies. We find significant differences between the SFHs of low mass (<10^11 M_sol) and high mass (>10^11 M_sol) galaxies. On average, low mass galaxies exhibit a dominant late burst of star formation which creates a large fraction of their stellar mass. Conversely, high mass systems tend to have a significant amount of stellar mass that formed much earlier. We also find that the high mass SFHs evolve more strongly than the low mass SFHs. These findings are consistent with the phenomenon of downsizing observed in optically selected samples of galaxies.