The bursting nature of star formation in compact star-forming galaxies from the Sloan Digital Sky Survey

TL;DR

This study analyzes ~14,000 low-redshift compact star-forming galaxies from SDSS, revealing that their luminosities are dominated by rapid, burst-driven star formation, which impacts the interpretation of their star formation rates and evolution.

Contribution

It introduces a correction method for rapid luminosity evolution due to starburst activity, refining the relation between stellar mass and star formation rate in compact galaxies.

Findings

Star formation in these galaxies is dominated by young bursts.

Correcting for burst age tightens the stellar mass–SFR relation.

Specific star formation rate is independent of stellar mass.

Abstract

We study integrated characteristics of ~14000 low-redshift (0<z<1) compact star-forming galaxies (SFGs) selected from the Data Release 12 of the Sloan Digital Sky Survey. It is found that emission of these galaxies is dominated by strong young bursts of star formation, implying that their luminosities experience rapid variations on a time scale of a few Myr. Reducing integrated characteristics of these galaxies to zero burst age would result in a considerably tighter and almost linear relation between stellar mass and star formation rate (SFR). The same correction implies that the specific star formation rate (the ratio of SFR and stellar mass) is not dependent on the galaxy stellar mass. We conclude that the correction for rapid luminosity evolution must be taken into account in a similar way when comparing different samples of low- and high-redshift SFGs. If the bursting nature of star formation and young burst ages are characteristics of the galaxies selected at high redshifts, the age correction of observed SFRs derived from the Hbeta emission line or UV continua would modify the derived SFR densities in the early universe.