Titans of the Early Universe: The seeds of the most massive high-z quasars
Intervenant : Tyrone Woods
Monash University, Melbourne
The discovery of billion solar mass high-redshift quasars challenges our understanding of the early Universe: how did such massive objects form in the first billion years? Observations and simulations increasingly favour the "direct collapse" scenario. In this case, an atomically-cooled gas cloud of primordial composition accretes rapidly onto a single stellar core, ultimately collapsing through the general relativistic instability after reaching ~100,000 solar masses and forming an initially massive seed black hole. Previous studies of such objects were either not hydrodynamical in nature, or considered their evolution in isolation, not in the extreme accretion flows in which they actually form. Here, we present our calculations using the stellar evolution code KEPLER, incorporating implicit hydrodynamics, GR corrections, and a detailed treatment of nuclear burning processes using an adaptive network. We find that the GR instability triggers collapse at 150,000-330,000 solar masses for accretion rates of 0.1-10 solar masses per year, providing the first mapping between the fates of such objects and the conditions under which they form. We discuss the response of these "supermassive stars" and their evolutionary state at the time of collapse for a wide range of accretion rates, and prospects for the ejection of chemically-enriched material.