Direct Collapse to Supermassive Black Hole Seeds with Radiative Transfer

主讲人 (Speaker): 罗阳

主讲人单位 (Speaker's Institute): 厦门大学天文系

邀请人 (Invited by): 申荣锋

时间 (Time): 星期一, 2018/12/24 - 10:30 to 12:00

地点 (Location): 珠海校区海滨红楼17栋107会议室

摘要 (Abstract):

A growing number of quasars found at redshifts z~6, when the universe was younger than a gigayear, requires a very efficient way of forming early supermassive black holes. The main difficulty in forming the SMBHs in galaxy centers is their long growth time, if the initial seed mass is small compared to the final product. In this work, we focus on direct collapse scenarios, in which gas accumulates and collapses to form an SMBH seed either with or without the intermediate stage of an super-massive star. In this work, we test this assumption by treating the optically thick part of the accretion flow using radiative transfer in the flux-limited diffusion (FLD) approximation. We follow the flow as the radiation pressure builds up and becomes as important as the gas thermal pressure. As a result, we find that the collapse proceeds in a filamentary way, and is nearly isothermal in the outer part, down to ~ 1e−4 − 1e−3 pc from the center. The gas is channeled along the filaments, with shocks formed by the material joining the filaments. Inside the optically-thick region, a central object forms in response to the converging flow and is delineated by its photosphere, initially ~ 1e−6 pc and expanding thereafter. The core radiation luminosity in the FLD run is of the order of the Eddington luminosity, and highly...

主讲人简介 (Speaker's CV):

Visiting Scholar / Postdoc in Xiamen University (2018.4 - ) Postdoc in University of Kentucky (2017.7 - 2018.4) Postdoc in Osaka University (2014.6 - 2017.6) Ph.D. from Xiamen University (2009.9 - 2014.6) B.S. from Hohai University (2004.9 - 2008.6) Research Interests: 1. Formation of Supermassive Black Hole Seed at High Redshift: Numerical Simulations, Intermediate-Mass BH Formation, First Quasar 2. Galaxy Formation and Evolution : X-ray Observations, Circum-Galactic Medium, Galactic Feedback 3. High Energy Phenomenon: Accretion Disks, X-ray Binaries, Gamma-ray Bursts.