Ultraluminous quasars at high redshift

Quasars at high redshift pinpoint the fastest-growing and most massive black holes as well as the first large galaxies forming in the early universe; they are also very useful as probes of the early intergalactic medium. Finding them has been a challenge, because they appear similar to cool stars in the Milky Way while being extremely rare. Using SkyMapper and WISE has allowed us to find quasars in the Southern sky, and adding Gaia DR2 has been a game changer in reducing stellar contamination. As a result, we are now finding quasars of unprecedented luminosity and black-hole mass. Our work has doubled the number of known bright high-redshift quasars, including the most luminous object overall. Here, we report on their properties, black-hole masses, plans to obtain a more complete sample and track the demographics of supermassive black holes in the early Universe.