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

Read, J. I. ; Goerdt, Tobias ; Moore, Ben ; Pontzen, A. P. ; Stadel, Joachim ; Lake, George

In: Monthly Notices of the Royal Astronomical Society, 2006, vol. 373, no. 4, p. 1451-1460

Zum persönliche Liste hinzufügen
    Summary
    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