Dynamical friction in constant density cores: a failure of the Chandrasekhar formula

被引:129
作者
Read, J. I.
Goerdt, Tobias
Moore, Ben
Pontzen, A. P.
Stadel, Joachim
Lake, George
机构
[1] Univ Zurich, Inst Theoret Phys, CH-8057 Zurich, Switzerland
[2] Univ Cambridge, Inst Astron, Cambridge CB3 0HA, England
关键词
galaxies : dwarf; galaxies : kinematics and dynamics;
D O I
10.1111/j.1365-2966.2006.11022.x
中图分类号
P1 [天文学];
学科分类号
0704 ;
摘要
Using analytic calculations and N-body simulations we show that in constant density (harmonic) cores, sinking satellites undergo an initial phase of very rapid (super-Chandrasekhar) dynamical friction, after which they experience no dynamical friction at all. For density profiles with a central power law profile, rho proportional to r(-alpha), the infalling satellite heats the background and causes a to decrease. For alpha < 0.5 initially, the satellite generates a small central constant density core and stalls as in the alpha = 0 case. We discuss some astrophysical applications of our results to decaying satellite orbits, galactic bars and mergers of supermassive black hole binaries. In a companion paper we show that a central constant density core can provide a natural solution to the timing problem for Fornax's globular clusters.
引用
收藏
页码:1451 / 1460
页数:10
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