CIII] Emission in Star-forming Galaxies at z ~ 1

TL;DR

This study analyzes CIII] emission in star-forming galaxies at z ~ 1, revealing that such emission is generally weaker and associated with younger, less dusty, low-mass galaxies, providing insights into galaxy properties during this epoch.

Contribution

First statistical analysis of CIII] emission in z ~ 1 galaxies, correlating emission strength with galaxy properties and environment, enhancing understanding of galaxy evolution.

Findings

CIII] equivalent width median is 1.30 Å, smaller than at z > 6.

Only 40 of 184 galaxies show significant CIII] detections.

Strong CIII] emitters tend to be young, low-mass, and less dusty galaxies.

Abstract

The CIII]{\lambda}{\lambda}1907, 1909 rest-frame UV emission doublet has recently been detected in galaxies during the epoch of reionization (z > 6), with high equivalent width (>10 {\AA}, rest frame). Currently, it is possible to obtain much more detailed information for star-forming galaxies at significantly lower redshift. Accordingly, studies of their far-UV spectra are useful for understanding the factors modulating the strength of CIII] emission. We present the first statistical sample of CIII] emission measurements in star-forming galaxies at z ~ 1. Our sample is drawn from the DEEP2 survey and spans the redshift 0.64 < z < 1.35 (<z> = 1.08). We find that the median equivalent width (EW) of individual CIII] detections in our sample (1.30 {\AA}) is much smaller than the typical value observed thus far at z > 6. Furthermore, out of 184 galaxies with coverage of CIII], only 40 have significant detections. Galaxies with individual CIII] detections have bluer colors and lower luminosities on average than those without, implying that strong CIII] emitters are in general young and low-mass galaxies without significant dust extinction. Using stacked spectra, we further investigate how CIII] strength correlates with multiple galaxy properties (M_B, U-B, M*, star-formation rate, specific star-formation rate) and rest-frame near-UV (FeII* and MgII) and optical [OIII] and H{\beta}) emission line strengths. These results provide a detailed picture of the physical environment in star-forming galaxies at z ~ 1, and motivate future observations of strong CIII] emitters at similar redshifts.