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

Journal article

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, ρ ∝ r -α, the infalling satellite heats the background and causes α to decrease. For α < 0.5 initially, the satellite generates a small central constant density core and stalls as in the α = 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. © 2006 RAS.

Authors: Read, J; Goerdt, T; Moore, B; Pontzen, A; Stadel, J

• Publication status: Published
• Journal: Monthly Notices of the Royal Astronomical Society
• Volume: 373
• Issue: 4
• Pages: 1451-1460
• Publication date: 2006-12-21
• DOI: 10.1111/j.1365-2966.2006.11022.x
• EISSN: 1365-2966
• ISSN: 0035-8711
• Language: English
• Keywords: galaxies : dwarf; galaxies : kinematics and dynamics