Linear kinetic theory of instabilities of a gravitating stellar disk
type: Item
instance of: scholarly article
title: Linear kinetic theory of instabilities of a gravitating stellar disk
zbMATH Open document ID: 0995.76081
DOI: 10.1023/A:1002091325620
author: Evgeny Griv
author: Michael Gedalin
author: David Eichler
author: Chi Yuan
published in: Astrophysics and Space Science
publication date: 2002-10-21T00:00:00Z
review text: The authors develop a linear kinetic theory to describe collective oscillations propagating in a rapidly rotating disk of stars, typical of a highly flattened galaxy. The analysis is carried out for a self-graviting, infinitesimally thin and spatially inhomogeneous system, taking into account the thermal motions of stars and gravitational encounters between stars and giant molecular clouds in interstellar medium. The star-cloud encounters are described by Landau collision integral, and the dynamics of gravity perturbations with rare interparticle encounters is also taken into account. Such a model can be treated by using the mathematical formalism from plasma perturbation theory, employing the normal-mode analysis. In particular, the authors solve the Boltzmann equation by integration along paths, neglegting the influence of star-cloud encounters on the star distribution in zeroth-order approximation. The kinetic effect is introduced via the drift notion of stars, which can be computed from the equations of stellar motion in unperturbed central force field of the galaxy. The authors obtain two dispersion laws for two main branches of disk oscillations, i.e. the classical Jeans branch, and an additional gradient branch. The resonant Landau-type instabilities of hydrodynamically stable Jeans branch and gradient gravity perturbations are shown to be long-term generating mechanisms for propagating density waves, thereby leading to spiral-like and/or ring-like patterns in flat galaxies.
Mathematics Subject Classification ID: 76P05
Mathematics Subject Classification ID: 85A15
zbMATH DE Number: 1508108
zbMATH Keywords: rigidly rotating stellar disk
zbMATH Keywords: self-graviting system
zbMATH Keywords: spiral-like patterns
zbMATH Keywords: linear kinetic theory
zbMATH Keywords: flattened galaxy
zbMATH Keywords: star-cloud encounters
zbMATH Keywords: Landau collision integral
zbMATH Keywords: plasma perturbation theory
zbMATH Keywords: normal-mode analysis
zbMATH Keywords: Boltzmann equation
zbMATH Keywords: Jeans branch
zbMATH Keywords: gradient branch
zbMATH Keywords: resonant Landau-type instabilities
zbMATH Keywords: gradient gravity perturbations
zbMATH Keywords: density waves
reviewed by: Agneta M. Balint
MaRDI profile type: Publication
full work available at URL: a:1002091325620
OpenAlex ID: W165754900
Wikidata QID: Q60716789
description: scientific article; zbMATH DE number 1508108