Evolution of the Rate and Mode of Star Formation in Galaxies since z=0.7

TL;DR

This study investigates how the star formation rate and mode in galaxies have evolved since redshift 0.7, revealing a sharp decline in both the rate and starburst activity, likely due to decreasing gas availability.

Contribution

It provides new measurements of star formation rates and starburst fractions at intermediate redshifts using multi-wavelength data, highlighting the evolution of star formation modes over time.

Findings

Significant decline in star formation rate since z=1

Rapid decrease in galaxy starburst fractions

Decline linked to reduced gas supply for star formation

Abstract

We present the star formation rate (SFR) and starburst fraction (SBF) for a sample of field galaxies from the ICBS intermediate-redshift cluster survey. We use [O II] and Spitzer 24 micron fluxes to measure SFRs, and 24 micron fluxes and H-delta absorption to measure of SBFs, for both our sample and a present-epoch field sample from the Sloan Digital Sky Survey (SDSS) and Spitzer Wide-area Infrared Extragalactic (SWIRE) survey. We find a precipitous decline in the SFR since z=1, in agreement with other studies, as well as a corresponding rapid decline in the fraction of galaxies undergoing long-duration moderate-amplitude starbursts. We suggest that the change in both the rate and mode of star formation could result from the strong decrease since z=1 of gas available for star formation.