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

Abstract

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 of log-slope, $-\alpha$, the infalling satellite heats the background and causes $\alpha$ 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.

11 pages, 7 figures. Final version accepted for publication in MNRAS

References in corpus (2)

• Does the Fornax dwarf spheroidal have a central cusp or core?
• Large scale inhomogeneity and local dynamical friction

Cited by in corpus (10)

• The ACS Virgo Cluster Survey. XII. The Luminosity Function of Globular Clusters in Early Type Galaxies
• Ejection of Supermassive Black Holes from Galaxy Cores
• The nucleus of the Sagittarius dSph galaxy and M54: a window on the process of galaxy nucleation
• The Causes of Halo Shape Changes Induced by Cooling Baryons: Disks Versus Substructures
• Small Dwarf Galaxies Within Larger Dwarfs: Why Some Are Luminous While Most Go Dark
• The formation of ultra-compact dwarf galaxies and nucleated dwarf galaxies
• Self-consistent simulations of Nuclear Cluster formation through Globular Cluster orbital decay and merging
• Dynamical friction of massive objects in galactic centres
• Constraints on the merging timescale of luminous red galaxies, or, where do all the halos go?
• Constraining dark matter sub-structure with the dynamics of astrophysical systems