Program: GN-2019A-FT-101

Quasars at the epoch of reionization provide direct probes to the evolution of supermassive black holes (SMBHs), the cosmic reionization hisotry, and the build-up of the most massive galaxies at cosmic dawn. However only couple of quasars previously known at z>6.8, because of a combination of their declining spatial density and limited sky coverage of near infrared photoemetry. Recently, we discovered a luminous quasar at z=6.83. Here, we propose to use Gemini/GMOS to obtain deep optical spectroscopic observations of this newly discovered quasar. The proposed observations and our scheduled near-infrared spectroscopic observations with KECK/NIRES will allow detailed modeling of quasar absorption spectra, including the profile of damping wing and proximity zone, which will provide new constraints on the intergalactic medium (IGM) neutral fraction at the cosmic reionzation era and constrain the life time of this quasar. This quasar is setting and only visible in the next few months, thus it fits well with the fast turnaround spirit and allow us to timely plan followup observations.