Dynamical Friction in Interacting Relativistic Systems

Article
Report number	arXiv:1906.05341 ; CERN-TH-2019-088
Title	Dynamical Friction in Interacting Relativistic Systems
Author(s)	Katz, Andrey (CERN ; Geneva U., CAP) ; Kurkela, Aleksi (CERN ; Stavanger U.) ; Soloviev, Alexander (Vienna, Tech. U.)
Publication	2019-08-14
Imprint	2019-06-12
Number of pages	33
Note	33 pages, 8 figures
In:	JCAP 2019 (2019) 017
DOI	10.1088/1475-7516/2019/08/017
Subject category	gr-qc ; General Relativity and Cosmology ; astro-ph.GA ; Astrophysics and Astronomy ; hep-ph ; Particle Physics - Phenomenology
Abstract	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 $v\approx c_s$. These corrections smoothen the ideal fluid discontinuity around the speed of sound and render the drag force a continuous function of velocity. We show that these corrections can be computed to a good approximation within effective theory of viscous fluid dynamics.
Copyright/License	preprint: (License: arXiv nonexclusive-distrib 1.0) publication: © 2019-2024 IOP Publishing Ltd and Sissa Medialab

$Matching of the bulk viscosity onto the parameters of the full kinetic theory. The bulk viscosity, normalized to the entropy density is maximized around $m \sim 10T$. In the limit of zero mass of the gas particle both viscosities recover a well known conformal limit, $\zeta \to 0$ and $\eta \to s T \tau/5$.$ $The drag force in interacting kinetic theory. The left panel demonstrates the passage from a medium that is ideal fluid at all scales ($R_{\rm min} \ll \tau $, black solid line) to a medium that is ideal gas at all scales ($R_{\rm max} \ll \tau$, black dotted line). The other lines correspond the systems where the mean free path interpolates between the dimensions of the system $R_{\rm min} < \tau < R_{\rm max}$ keeping the external dimensions of the system fixed $R_{\rm max}/R_{\rm min}=10^{12}$. The right panel demonstrates the effect of the external dimensions of the system. The different lines correspond to different UV- and IR-cutoffs: the black solid line corresponds to an infinite system, whereas the other lines correspond to finite systems with different $R_{\rm max}/R_{\rm min}$ ratios with a fixed $R_{\rm max}/\tau = \tau/R_{\rm min}$.$ $The dynamical friction in ideal gas. The left panel shows the force in the regime of relativistic or nearly-relativistic gas, comparing the effect to the ultra-relativistic approximation. The right panel shows the drag force in largely non-relativistic gas. The solid lines show the exact result, while the dashed lines stand for the non-relativistic approximation of \cite{1943ApJ....97..255C}. The dashed-dotted light blue line stands for the approximation of the relativistic projectile in a non-relativistic medium, Eq.~\eqref{eq:fastbulletslowgas}.$ Show more plots

Corresponding record in: Inspire

Back to search

Record created 2019-06-29, last modified 2024-08-06

Registos similares

Fulltext:

PDF

Add to personal basket
Export as BibTeX, MARC, MARCXML, DC, EndNote, NLM, RefWorks

CERN Document Server

Access articles, reports and multimedia content in HEP

Main menu

CERN Accelerating science