Chandrasekhar Dynamical Friction
A perturber moves through a Maxwellian background of test particles. Gravitational focusing builds an overdense wake behind it; the back-reaction is Chandrasekhar dynamical friction, $a_{fric} \propto \rho \ln(\Lambda) f(X)$ with $X = V / (\sqrt{2}\sigma)$. The perturber visibly decelerates.
WHAT TO TRY
- Raise the perturber mass: the inspiral steepens sharply (the sinking rate scales with M), the satellite reaches the centre far sooner, and the trailing wake grows denser.
- Watch the r(t) diagnostic: the curve is not a straight line, it bends downward and accelerates, because r dr/dt is roughly constant so the orbit shrinks ever faster.
- Look behind the satellite: the luminous overdensity is the gravitational wake whose pull, not any drag medium, is what decelerates the satellite.