Program: GS-2019B-Q-134

The highest redshift quasars provide direct probes of the evolution of supermassive black holes (SMBHs) and the intergalactic medium at the earliest cosmic times. However, only few z>7 quasars were previously known, due to the challenges of NIR photometric selection and spectroscopic follow-up. Using newly available deep wide-field optical, near-IR, and middle-IR surveys, we have developed an efficient selection and follow-up technique to search for the highest redshift quasars, which has resulted in the discovery of more than 30 new quasars at z>6.5, including five objects at z>6.8 quasars, two at z>7 and the redshift holder quasar at z=7.5. This proposal aims to utilize the sensitive NIR capabilities of Gemini-N/GNIRS and Gemini-S/Flamingos-2 to extend our z>7 quasar search to the still unexplored sky. We propose to observe ~60 quasar candidates with Gemini which should uncover ~10 quasars at z>6.7 including 1-2 quasars at z>7. The proposed quasar survey will construct the first large statistical sample of z>7 quasars and provide the most powerful observational probes of early SMBH growth, the cosmic reionization history and the build-up of the most massive galaxies at cosmic dawn.