Book contents
- Frontmatter
- Contents
- Preface
- 1 Introduction
- 2 Observational Facts
- 3 Cosmological Background
- 4 Cosmological Perturbations
- 5 Gravitational Collapse and Collisionless Dynamics
- 6 Probing the Cosmic Density Field
- 7 Formation and Structure of Dark Matter Halos
- 8 Formation and Evolution of Gaseous Halos
- 9 Star Formation in Galaxies
- 10 Stellar Populations and Chemical Evolution
- 11 Disk Galaxies
- 12 Galaxy Interactions and Transformations
- 13 Elliptical Galaxies
- 14 Active Galaxies
- 15 Statistical Properties of the Galaxy Population
- 16 The Intergalactic Medium
- A Basics of General Relativity
- B Gas and Radiative Processes
- C Numerical Simulations
- D Frequently Used Abbreviations
- E Useful Numbers
- References
- Index
C - Numerical Simulations
Published online by Cambridge University Press: 05 June 2012
- Frontmatter
- Contents
- Preface
- 1 Introduction
- 2 Observational Facts
- 3 Cosmological Background
- 4 Cosmological Perturbations
- 5 Gravitational Collapse and Collisionless Dynamics
- 6 Probing the Cosmic Density Field
- 7 Formation and Structure of Dark Matter Halos
- 8 Formation and Evolution of Gaseous Halos
- 9 Star Formation in Galaxies
- 10 Stellar Populations and Chemical Evolution
- 11 Disk Galaxies
- 12 Galaxy Interactions and Transformations
- 13 Elliptical Galaxies
- 14 Active Galaxies
- 15 Statistical Properties of the Galaxy Population
- 16 The Intergalactic Medium
- A Basics of General Relativity
- B Gas and Radiative Processes
- C Numerical Simulations
- D Frequently Used Abbreviations
- E Useful Numbers
- References
- Index
Summary
In the main text we have seen that galaxy formation involves many physical processes. In broad terms these processes can be divided into three main categories: gravitational, gas-dynamical and radiative. Although the physical principles governing most of these processes are well established, the dynamical systems are often so complicated that it is generally difficult to obtain analytical solutions. Thanks to the revolutionary development of powerful computers, it has become possible to tackle some of these problems using numerical simulations. In a numerical simulation, the mass distribution is usually represented by particles or sampled on a grid, and the motion of each mass element is traced numerically by taking into account its interactions with other mass elements. The solutions would be exact if we were able to simulate the motions of all individual atoms or elementary particles. Unfortunately this can never be achieved since the systems of interest (galaxies) contain of the order of 1068 protons. In practice, therefore, the pseudo-particles or mass elements used to represent the mass distribution each have a mass that is typically orders of magnitude larger than that of an actual atom. Such a representation is clearly an approximation, which may impose serious limitations on the reliability of the simulations.
In general, numerical simulations of galaxy formation can be divided in two broad categories: N-body simulations and hydrodynamical simulations. Given the importance of numerical simulations in modern astrophysics, this appendix briefly describes some of the basic numerical methods used.
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- Galaxy Formation and Evolution , pp. 764 - 774Publisher: Cambridge University PressPrint publication year: 2010