IRAP > Seminars > Calendrier des séminaires > Titans of the Early Universe: The seeds of the most massive high-z quasars

Titans of the Early Universe: The seeds of the most massive high-z quasars

Séminaire le 15 Feb 2018 de 11h00 à 12h00

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.

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