|Time:||Tuesday, January 16, 2018, 02:00pm|
|Title:||Black hole evolution: from stellar mass to ultra-massive ones|
|Speaker:||Dr. Kohei Inayoshi (Columbia University)|
Observations of bright quasars at high-redshift have revealed that supermassive black holes (SMBHs) with billions solar masses already exist only within one billion year after the Big Bang. The discoveries in recent decades provide a challenging puzzle about the origin of SMBHs. In this talk, I will discuss two physical processes to form such monster BHs. The first one is formation of heavy seed BHs due to direct-collapse of massive metal-poor gas clouds in the first galaxies. The second is rapid BH growth at accretion rates exceeding the standard Eddington value. We find global accretion solutions from galactic scales down to the nuclear region at hyper-Eddington rates, unimpeded by radiation feedback. I will apply our results from radiation-hydrodynamical simulations to the cosmological evolution of BHs, and discuss the observational signatures from such bright systems.
Dr. Kohei Inayoshi obtained his Ph.D. degree in Physics from Kyoto University, Japan in 2014. He has been working at Columbia University, USA as a JSPS Postdoctoral Fellow (2014-2015) and a Junior Fellow, Simons Society of Fellows (2015-present).