Extreme Quasars During the Cosmic Dawn
Xiaohui Fan - University of Arizona
The most distant quasars provide unique probes to the formation of the earliest supermassive black holes, the co-evolution of early massive galaxies and their central black holes and the reionization of the intergalactic medium. More than 100 quasars have been discovered at z>6. I will present progress on surveys of the most distant quasars, focusing on three recent discoveries: (1) the most distant quasars known to date at z~7.5-7.6 and the constraint on cosmic reionization history; (2) the most luminous quasar at z>6 powered by a twelve billion solar mass black hole and its implications on the seed of the earliest supermassive black holes; and (3) the first gravitationally lensed quasar during the epoch of reionization and the prospect of direct black hole mass measurements at cosmic dawn.