14/9/22-14/9/28
SHAO Astrophysics Colloquia
MHD Simulations of Radiation Pressure Dominated Accretion Disks
Speaker: James Stone (Princeton University)
Time: Thursday, 3:00pm, September 25th
Location: Lecture Hall, 3rd floor
Abstract: For black holes accreting at anything more than a small fraction of the Eddington limit, the inner regions of the flow will be dominated by radiation rather than gas pressure. I will present results from a new study of the magnetohydrodynamics of accretion disks in this regime, using new numerical methods based on a formal solution of the radiation transfer equation using short characteristics, rather than the flux-limited diffusion approximation. For gas pressure dominated disks, long-lived stable vertical structures in which turbulent heating is balanced by radiative cooling are observed. However, when radiation pressure greatly exceeds gas pressure, we find the disk always undergoes a thermal runaway, either collapsing or expanding over several thermal times. The physics of this runaway is quite different from the classical linear instability in radiation dominated alpha disks predicted by Shakura and Sunyaev. Saturation of the runaway will require global models of radiation pressure dominated accretion flows, and we discuss future work on this problem.
Group meetings and additional talks
Blackhole accretion and High-energy astrophysics Seminar
Location: 1608; Contact: Qixiang Yang <qxyang@shao.ac.cn>
Title: Maintaining Low Star Formation Rates in Early-Type Galaxies with AGB Heating
Speaker: Zhaoming Gan
Time: Tuesday, 2:00 pm, Sep 23
Stellar Cluster and Galaxy Seminar group seminar
Location: 1617; Contact: Jianling Gan <jlgan@shao.ac.cn>
Speaker: Maria Carmen Argudo
Time: Wednesday, 10:30pm, Sep 24
Galaxies Group Journal Club
Location: 1608; Contact: Zhi Li <lizh@shao.ac.cn>
Title: 3D self-consistent N-body barred models of the Milky Way
Speaker: Min Du
Time: Thursday, 10:30am, Sep 25
Visitors
James Stone (Princeton University)
Dates: 23/09-27/09
Office: 1618
Host: Feng Yuan
Research interests: nonlinear and multidimensional fluid dynamics
Newcomers
Name: Maria Carmem Argudo
Office: 1517
Position: Postdoctoral researcher
Research interests: galaxies and environment, isolated galaxies
