C III] Emission in Star-Forming Galaxies Near and Far

TL;DR

This study compares C III] emission in star-forming galaxies across different redshifts, revealing that strong emission is not universal and is associated with low-metallicity, starburst galaxies, providing insights into early universe star formation conditions.

Contribution

It provides the first comparative analysis of C III] emission in both high-redshift and local star-forming galaxies, highlighting its non-universality and association with specific galaxy properties.

Findings

Lower C III] equivalent widths in high-redshift galaxies than previously reported.

20% of local galaxies show strong C III] emission, often in Wolf-Rayet galaxies.

Strong C III] emission correlates with low metallicity and intense star formation.

Abstract

We measure C III] 1907,1909 A emission lines in eleven gravitationally--lensed star-forming galaxies at z~1.6--3, finding much lower equivalent widths than previously reported for fainter lensed galaxies (Stark et al. 2014). While it is not yet clear what causes some galaxies to be strong C III] emitters, CIII] emission is not a universal property of distant star-forming galaxies. We also examine C III] emission in 46 star-forming galaxies in the local universe, using archival spectra from GHRS, FOS, and STIS on HST, and IUE. Twenty percent of these local galaxies show strong C III] emission, with equivalent widths <-5 A. Three nearby galaxies show C III] emission equivalent widths as large as the most extreme emitters yet observed in the distant universe; all three are Wolf-Rayet galaxies. At all redshifts, strong C III] emission may pick out low-metallicity galaxies experiencing intense bursts of star formation. Such local C III] emitters may shed light on the conditions of star formation in certain extreme high-redshift galaxies.