Book contents
- Frontmatter
- Contents
- Preface
- Introduction
- Part I Idealized homogeneous systems – basic ideas and gentle relaxation
- Part II Infinite inhomogeneous systems – galaxy clustering
- 20 How does matter fill the Universe?
- 21 Gravitational instability of the infinite expanding gas
- 22 Gravitational graininess initiates clustering
- 23 Growth of the two-galaxy correlation function
- 24 The energy and early scope of clustering
- 25 Later evolution of cosmic correlation energies
- 26 N-body simulations
- 27 Evolving spatial distributions
- 28 Evolving velocity distributions
- 29 Short review of basic thermodynamics
- 30 Gravity and thermodynamics
- 31 Gravithermodynamic instability
- 32 Thermodynamics and galaxy clustering; ξ(r)∝r-2
- 33 Efficiency of gravitational clustering
- 34 Non-linear theory of high order correlations
- 35 Problems and extensions
- 36 Bibliography
- Part III Finite spherical systems – clusters of galaxies, galactic nuclei, globular clusters
- Part IV Finite flattened systems – galaxies
- Index
21 - Gravitational instability of the infinite expanding gas
Published online by Cambridge University Press: 05 July 2011
- Frontmatter
- Contents
- Preface
- Introduction
- Part I Idealized homogeneous systems – basic ideas and gentle relaxation
- Part II Infinite inhomogeneous systems – galaxy clustering
- 20 How does matter fill the Universe?
- 21 Gravitational instability of the infinite expanding gas
- 22 Gravitational graininess initiates clustering
- 23 Growth of the two-galaxy correlation function
- 24 The energy and early scope of clustering
- 25 Later evolution of cosmic correlation energies
- 26 N-body simulations
- 27 Evolving spatial distributions
- 28 Evolving velocity distributions
- 29 Short review of basic thermodynamics
- 30 Gravity and thermodynamics
- 31 Gravithermodynamic instability
- 32 Thermodynamics and galaxy clustering; ξ(r)∝r-2
- 33 Efficiency of gravitational clustering
- 34 Non-linear theory of high order correlations
- 35 Problems and extensions
- 36 Bibliography
- Part III Finite spherical systems – clusters of galaxies, galactic nuclei, globular clusters
- Part IV Finite flattened systems – galaxies
- Index
Summary
They [atoms] move in the void and catching each other up jostle together, and some recoil in any direction that may chance, and others become entangled with one another in various degrees according to the symmetry of their shapes and sizes and positions and order, and they remain together and thus the coming into being of composite things is effected.
SimpliciusWhat types of structure arise from the instability of homogeneous gravitating systems? This is the fundamental question we can now tackle by extending the techniques of Part 1. Eventually we will compare the results with the observed features described in Section 20, and see how these simple initial conditions can account for the main properties of galaxy clustering, but not for the origin of the galaxies themselves.
Many detailed calculations, starting in the mid-1960s but based on the pioneering work of Lifshitz (1946) and Bonnor (1957), have examined the growth of local gaseous instabilities in expanding cosmological models. They treat interactions between gas and radiation, showing mainly how electron scattering damps the growth of large amplitude isothermal perturbations before the era of decoupling, and how radiation viscosity damps small adiabatic perturbations during decoupling. They treat interactions of gas with massive collisionless particles such as heavy neutrinos, and with seeds of finite amplitude gravitational instabilities such as black holes or other condensed pregalactic objects.
- Type
- Chapter
- Information
- Gravitational Physics of Stellar and Galactic Systems , pp. 151 - 157Publisher: Cambridge University PressPrint publication year: 1985