S21A0072
S21A0072
We propose to use Keck/MOSFIRE to obtain rest-frame UV spectra of six newly identified ultra-bright z > 7 galaxies. All of our targets have an accurate redshift determined using the [CII]158µm line with ALMA. These galaxies are so far the only sample of z > 7 galaxies where we can systematically look for Lyα emission, while already having the systemic redshifts and information on dust emission. Recent unexpected detections of Lyα emission in a handful of bright UV galaxies during the Epoch of Reionization (z > 7) appear to have harder ionizing spectra. This may indicate early formation of large ionizing bubbles hosted by yet to be probed luminous galaxies. With our on-going ALMA Large Program, REBELS, we have been systematically searching for z > 6.5 massive galaxies and are increasing the known z > 7 spectroscopic samples by a factor of 2-3. Here, we will look for Lyα emission in all REBELS’s z > 7 [CII] emitters which are accessible in the S21A semester. We will (1) assess the prevalence of Lyα emission during the reionization epoch, (2) evaluate properties of the intergalactic medium using Lyα line profiles, and (3) use the UV line N V to obtain constraints on the fraction of luminous sources that harbor active galactic nuclei.
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