Simulating gas accretion onto the first supermassive black holes
Intervenant : Ricarda Beckmann
The first supermassive black holes were observed as quasars at redshift z=7, at which point they had already reached masses in excess of a billion solar masses. To put this in context, this corresponds to black holes a thousand times more massive than the one we observe today, but when the Universe was only a few hundred million years old. To become so massive, seed black holes must have grown by orders of magnitude through gas accretion or mergers, with particularly gas accretion expected to play a major role in the gas rich early universe. How much mass a black hole is able to gain via gas accretion is determined both by the global gas supply, and by the detailed structure of gas in the black hole vicinity. The origin and evolution of these supermassive black holes is therefore a problem that requires tracking gas flows over many orders of magnitude, from cosmic filaments on Mpc scales to the last stable orbit and event horizon of a few astronomical units. Using the black hole zoom algorithm to resolve the immediate black hole environment by orders of magnitude above that of that of the host galaxy, the hydrodynamical simulations presented here are able to follow the early black hole evolution in great detail. This work demonstrates the importance of sub-pc size gas features for the accretion duty cycle of the black hole, highlights the importance of dynamics of the black hole within its host, and sheds light on the early co-evolution between supermassive black hole progenitors and their host galaxies at redshift z>10.