Cake Talk by Anna-Christina Eilers from Massachusetts Institute of Technology
The existence of luminous quasars hosting supermassive black holes within the first billion years of cosmic history challenges our understanding of black hole growth. An important piece of the puzzle is the lifetime of quasars - the time that galaxies shine as active quasars and during which the bulk of the black hole growth occurs - but to date its value remains uncertain by several orders of magnitude. I will present a new method to obtain constraints on the lifetime of quasars based on the sizes of ionized regions around quasars known as proximity zones. These proximity zones act as a "quasar clock" and enable us to study the co-evolution of supermassive black holes and their host galaxies from a new perspective. Surprisingly, our results indicate that black holes might be able to grow several orders of magnitude faster than previously thought. I will show how future observations with the upcoming James Webb Space Telescope will enable new insights into the early assembly of supermassive black holes and galaxy-quasar co-evolution across cosmic time.