Dynamical friction in ultralight dark matter: Plummer sphere perspective

Abstract

In models of dark matter composed of feebly interacting ultralight bosons in the state of Bose-Einstein condensate, the dynamical friction force acting on circularly moving globular clusters modelled as Plummer spheres is determined. Analytic expressions for both radial and tangential components of the dynamical friction force are given. We reveal that the dynamical friction force for the Plummer sphere deviates from that for a point probe of the same mass for a significantly large ratio of the Plummer sphere radius to its orbital radius, as well as for large values of the Mach number.