Star formation activity in Balmer break galaxies at $z$ < 1.5

TL;DR

This study analyzes star formation activity in Balmer break galaxies across a range of redshifts up to 1.5, revealing correlations between star formation rates, stellar mass, and color, and suggesting a characteristic mass and color for galaxy evolution.

Contribution

It provides new spectroscopic data on Balmer break galaxies up to z=1.5, identifying a break in star formation relations related to galaxy mass and color evolution.

Findings

SFR correlates with stellar mass with a notable break at high masses.

SSFR anticorrelates with stellar mass, with a break indicating massive galaxies with lower SSFR.

High-redshift galaxies show higher SFR and SSFR at a given mass compared to local galaxies.

Abstract

Aims. We present a spectroscopic study of the properties of 64 Balmer break galaxies that show signs of star formation. The studied sample of star-forming galaxies spans a redshift range from 0.094 to 1.475 with stellar masses in the range 10$^{8}-$10$^{12}$ $M_{\odot}$. The sample also includes eight broad emission line galaxies with redshifts between 1.5 $<z<$ 3.0. Methods. We derived star formation rates (SFRs) from emission line luminosities and investigated the dependence of the SFR and specific SFR (SSFR) on the stellar mass and color. Furthermore, we investigated the evolution of these relations with the redshift. Results. We found that the SFR correlates with the stellar mass, our data is consistent with previous results from other authors in that there is a break in the correlation, which reveals the presence of massive galaxies with lower SFR values (i.e., decreasing star formation). We also note an anticorrelation for the SSFR with the stellar mass. Again in this case, our data is also consistent with a break in the correlation, revealing the presence of massive star-forming galaxies with lower SSFR values, thereby increasing the anticorrelation. These results might suggest a characteristic mass ($M_{0}$) at which the red sequence could mostly be assembled. In addition, at a given stellar mass, high-redshift galaxies have on average higher SFR and SSFR values than local galaxies. Finally, we explored whether a similar trend could be observed with redshift in the SSFR$-(u-B)$ color diagram, and we hypothesize that a possible $(u-B)_{0}$ break color may define a characteristic color for the formation of the red sequence.