Studying CIII] Emitters with MUSE

Michael Maseda (Leiden)
January 26, 2018 - 12:15pm


The CIII] emission doublet (1907,1909 Angstroms) has been proposed as an alternative to Lyman-alpha in redshift confirmations of galaxies at z > 6 since it is not attenuated by the largely neutral intergalactic medium at these redshifts and is believed to be strong in the young, vigorously star-forming galaxies present at these early cosmic times. I will present a statistical sample of 17 CIII]-emitting galaxies beyond z=1.5 using 30-h deep VLT/MUSE integral field spectroscopy covering 2 square arcminutes in the Hubble Deep Field South (HDFS) and Ultra Deep Field (UDF), achieving C III] sensitivities of ~1e-17 erg/s/cm2. The rest-frame equivalent widths range from 2 to 19 Angstroms. These 17 galaxies represent 3% of the total sample of galaxies found between 1.5 < z < 4. They also show elevated star formation rates, lower dust attenuation, and younger mass-weighted ages than the general population of galaxies at the same redshifts. Combined with deep slitless grism spectroscopy from the HST/WFC3 in the UDF, we can tie the rest-frame ultraviolet C III] emission to rest-frame optical emission lines, namely [O III] 5007, finding a strong correlation between the two. Down to the flux limits that we observe, all objects with a rest-frame [O III] equivalent width in excess of 250 Angstroms, the so-called extreme emission line galaxies, have detections of CIII] in our MUSE data. More detailed studies of the C III]-emitting population at these intermediate redshifts will be crucial to understand the physical conditions in galaxies at early cosmic times and to determine the utility of C III] as a redshift tracer.