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

Jane R. Rigby, Matthew B. Bayliss, Michael D. Gladders, Keren Sharon, Eva Wuyts, Hakon Dahle, Traci Johnson, Maria Pena-Guerrero

Published 2015-10-09Version 1

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.