Dynamical Friction in Interacting Relativistic Systems

Understand

We study dynamical friction in interacting relativistic systems with arbitrary mean free paths and medium constituent masses.

• Our novel framework recovers the known limits of ideal gas and ideal fluid when the mean free path goes to infinity or zero, respectively, and allows for a smooth interpolation between these limits.
• We find that in an infinite system the drag force can be expressed as a sum of ideal-gas-like and ideal-fluid-like contributions leading to a finite friction even at subsonic velocities.
• This simple picture receives corrections in any finite system and the corrections become especially significant for a projectile moving at a velocity $v$ close to the speed of sound $v\approx c_s$.