Abstract

High-redshift quasars, powered by accretion of supermassive black holes, provide unique probe to the formation of black holes in the early universe, the co-evolution of black holes and their host galaxies, and the contribution of black accretion to cosmic reionization. I will review recent results from new high-redshift quasar surveys, focusing on the first discoveries of quasars with 10 billion solar mass black holes at the end of reionization; their existence might require direct collapse of massive black hole seeds at early epochs. I will present new ALMA observations on the host galaxies of luminous z>6 quasars. which have high star formation rates accompanied by modest host masses, implying strong evolution of black hole/galaxy mass relation at high-redshift. I will also discuss recent determinations of high-redshift quasar luminosity function, which show a surprisingly high characteristic luminosity and call for a re-evaluation of the role of AGN in cosmic reionization through a more complete census of faint high-redshift quasar population.