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Newsletter

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  

 
About
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Research Center for Galaxy and Cosmology is the division engaging on the astrophysical research in Shanghai Astronomical Observatory. The research area includes cosmology, large scale structure, galaxy formation and evolution, the active galactic nucleus and compact objects, the star cluster and the structure of the Milk Way etc.

CGC participates in many international sky survey projects, including the LAMOST sky survey, the Sloan Digital Sky Survey IV ,BigBoss,LSST etc. CGC maintains close partnerships with many astronomical   research institutes.

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