Program: GN-2020B-FT-109

We propose GNIRS spectroscopy of a promising high-redshift quasar candidate PSO J352+11 at z~7. PSO J352+11 has been independently detected by several different surveys, the PS1, UKIDSS LAS, and WISE surveys. It also has a radio counterpart in the FIRST survey catalog of 1.4 GHz radio sources. Similar to known quasars at z>6.5 discovered in the PS1 survey, PSO J352+11 is detected only in the PS1 y band and not in the bluer bands. The near-infrared spectral energy distribution (SED) of PSO J352+11 is consistent with the SED of a quasar at z=7.2. The global optical-to-radio SED of PSO J352+11 is consistent with that of a radio-loud quasar. Our goal is to obtain spectroscopic confirmation of the quasar origin of PSO J352+11 by detecting prominent quasar emission lines (CIV, CIII], MgII) and the Lyman alpha break (the Gunn-Peterson trough). The GNIRS data will allow us to measure the continuum luminosity, black hole mass and accretion rate of PSO J352+11. If confirmed, PSO J352+11 will be the most distant radio-loud quasar known which can provide new insights on evolution of quasars, theory of jet formation and supermassive black hole – galaxy co-evolution.