Effects of the energy equation in studies of limit-cycle behaviors of black hole accretion disks  

作　　者：XUE Li LU JuFu 

机构地区：[1]Department of Physics and Institute of Theoretical Physics and Astrophysics,Xiamen University,Xiamen 361005,China

出　　处：《Science China(Physics,Mechanics & Astronomy)》2009年第6期954-959,共6页中国科学：物理学、力学、天文学（英文版）

基　　金：Supported by the National Basic Research Program of China (Grant No.2009CB824800);the National Natural Science Foundation of China (Grant Nos.10673009 and 10833002);the Natural Science Foundation of Fujian Province of China (Grant No.V0750001)

摘　　要：The inconsistency of the energy equation used in the literature is pointed out and a new consistent energy equation is given. With this new energy equation, calculations are made for the limit-cycle behaviors of thermally unstable accretion disks around black holes. From the comparison of our numerical results with those obtained using the inconsistent energy equation, it is found that the inconsistent energy equation undervalues the temperature and overvalues the effective optical depth when the accreted gas becomes effectively optically thin. Thus, it is dangerous if the inconsistent energy equation is used in the studies of very hot and optically thin accretion flows such as advection-dominated accretion flows (ADAFs), and our new energy equation is likely to be a better alternative.The inconsistency of the energy equation used in the literature is pointed out and a new consistent energy equation is given. With this new energy equation, calculations are made for the limit-cycle behaviors of thermally unstable accretion disks around black holes. From the comparison of our numerical results with those obtained using the inconsistent energy equation, it is found that the inconsistent energy equation undervalues the temperature and overvalues the effective optical depth when the accreted gas becomes effectively optically thin. Thus, it is dangerous if the inconsistent energy equation is used in the studies of very hot and optically thin accretion flows such as advection-dominated accretion flows (ADAFs), and our new energy equation is likely to be a better alternative.

关 键 词：accretion: ACCRETION DISKS black hole physics HYDRODYNAMICS INSTABILITIES 

分 类 号：P145.8[天文地球—天体物理]