Cosmological models with fluid matter undergoing velocity diffusion
type: Item
instance of: scholarly article
title: Cosmological models with fluid matter undergoing velocity diffusion
zbMATH Open document ID: 1255.83017
author: Simone Calogero
published in: Journal of Geometry and Physics
publication date: 2012-09-26T00:00:00Z
full work available at URL: https://arxiv.org/abs/1202.4888
reviewed by: Anil Zenginoglu
Mathematics Subject Classification ID: 83C05
Mathematics Subject Classification ID: 83F05
Mathematics Subject Classification ID: 83C55
Mathematics Subject Classification ID: 83C20
Mathematics Subject Classification ID: 83C75
zbMATH DE Number: 6086948
zbMATH Keywords: diffusion
zbMATH Keywords: cosmology
zbMATH Keywords: accelerated expansion
zbMATH Keywords: scalar field
MaRDI profile type: Publication
OpenAlex ID: W1974179786
arXiv ID: 1202.4888
cites work: Relativistic diffusions and Schwarzschild geometry
cites work: Relativistic diffusion with friction on a pseudo-Riemannian manifold
cites work: Exact Solutions of Einstein's Field Equations
cites work: Q3518447
DOI: 10.1016/J.GEOMPHYS.2012.06.004
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review text: The author presents a model for diffusion in general relativity and discusses how the inclusion of diffusion effects the global dynamics of simple cosmological spacetimes. The paper is a shorter version of a previous publication by the author [``A kinetic theory of diffusion in general relativity with cosmological scalar field'', J. Cosm. Astrop. Phys. 11, 016 (2011)].NEWLINENEWLINEThe galaxies are represented as fluid particles that undergo velocity diffusion in a background medium provided by a cosmological scalar field. The diffusion process is modeled by an energy-momentum tensor whose divergence is proportional to the fluid flow (number density times the four-velocity). The proportionality constant is called the diffusion constant. In previous work, the author derives this rather ad-hoc looking term from relativistic kinetic theory.NEWLINENEWLINEA cosmological scalar field is added to ensure consistency with the Einstein equations that satisfy the Bianchi identity. However, the canonical energy-momentum tensor of this scalar field is not added as a source to the Einstein equations.NEWLINENEWLINEThe author studies the consequences of this diffusion model for spatially homogeneous and isotropic solutions (Friedman-Lemaître-Robertson-Walker metrics) with vanishing spatial curvature. Depending on the choice of initial data parameters, the global dynamics of the cosmological spacetime can be very different when diffusion is included.NEWLINENEWLINEIt would be interesting to apply the knowledge gained from this analysis of general relativistic diffusion to physical cosmology.
description: scientific article; zbMATH DE number 6086948