Abstract

The Prevalence of CIII Emission at 1 < z < 4

Michael Maseda (Leiden Observatory)

Jarle Brinchmann (Leiden), Marijn Franx (Leiden), and the MUSE GTO team

While large samples of z>6 galaxies have been constructed using deep optical and near-IR imaging using the Lyman-break technique, relatively few of those candidates have been confirmed spectroscopically. Much of the difficulty is caused by the increasingly neutral intergalactic medium at these redshifts, which would attenuate the Lyman-alpha emission that is relied upon to confirm the redshifts. Some authors have posited that other, relatively strong emission lines can be used to confirm redshifts at z>6, namely semi-forbidden CIII] 1907/9. While observed in a small sample of lensed galaxies at high-z, it is not understood exactly what correlates with the strength of CIII] emission. Here we combine extremely deep optical spectroscopy with MUSE in the UDF and HDF-S to systematically obtain a sample of (unlensed) 1.2 < z < 3.8 CIII] emitters. With a number of significant detections of CIII], we investigate the prevalence of the emission with properties such as M*, sSFR, UV luminosity, and rest-optical emission (from near-IR spectroscopy with 3D-HST) compared to the non-emitting population. The presence of CIII] and other rest-UV lines (such as CIV, HeII, and OIII) in the deep MUSE data motivates us to obtain deep, high-S/N spectroscopy with NIRSpec, which will be useful to both confirm galaxy redshifts when the strong rest-optical emission features are redshifted out of coverage (z>12) and also to allow us to understand the physical properties of galaxies at all redshifts.

Talk