Program: GN-2021A-Q-110

We propose for Gemini-N GNIRS spectroscopy of an extremely large equivalent-width (EW) Lyman-alpha emitter (LAE) at z=7.608 with EW=280A, which was discovered lately from Keck/MOSFIRE observations in Jung et al. (2020). The existence of such large EW LAE at this redshift is surprising and hardly expected as the visibility of Lyman-alpha decreases with an increasing neutral fraction of the intergalactic medium into the epoch of reionization. Particularly, this galaxy was found as one of the four LAEs clustered in close physical separation, which form contiguous localized ionized bubbles. However, sole detection of Lyman-alpha does not provide enough information for investigating detailed galaxy properties that are tied to ionizing photon production and escape from a galaxy. The detection of UV metal lines in addition to Lyman-alpha is necessary to constrain the interstellar medium kinematics, source and strength of ionization, metallicity, and stellar population properties of this galaxy. Gemini-N/GNIRS provides a unique opportunity of efficiently targeting these prominent UV spectral lines simultaneously (C III], Si III], C IV, and N V). We request ~6hr Gemini-N observing time with GNIRS to observe these UV metal lines as well as revisiting Lyman-alpha of this galaxy. The observation will bring invaluable information for answering the quesion: what powers such strong Lyman-alpha from a galaxy and creates an ionized bubble during the epoch of reionization?