Carla Bernhardt ( USA )
carla.j.bernhardt @ gmail.com
Birth and Evolution of Primeval Quasars
The existence of billion solar mass black holes at z ~ 7 (and now even a 12 billion solar mass BH at z = 6.3) pose severe challenges to current paradigms of cosmological structure formation because it is not known how objects so massive formed by such early times in the universe. It is believed that 100,000 solar mass black holes forming via direct collapse in atomically cooling halos at z ~ 18 - 20 are the seeds of these SMBHs. But the formation of a direct-collapse black hole (DCBH) does not guarantee it will become supermassive -- it must happen at the intersection of strong, cold accretion flows like those thought to fuel the rapid growth of galaxies at later epochs that are capable of depositing a billion solar masses of gas in the host halo in 500 Myr. I will simulate this process in the Enzo AMR cosmological code with full x-ray transport to determine if the seed BH can still reach a billion solar masses by z ~ 7 without dispersing the cold flows that feed it. We will also calculate the 21 cm and NIR signatures of the SMBH down through cosmic time to evaluate prospects for its detection by JWST, E-ELT and the SKA. I will also model in detail the birth of the seed itself on much smaller spatial scales, simulating x-ray breakout into the primeval IGM and calculating the luminosity of the nascent quasar in the NIR and x-rays. The goal of these models will be to determine if quasar birth at the earliest epochs will be visible to next-generation telescopes and if x-ray feedback from the DCBH allow it to initially grow at the Eddington limit, as it must to become supermassive by z ~ 7.
Supervisor: Ralf Klessen (ITA)