Book contents
- Frontmatter
- Contents
- List of contributors
- Preface
- Acknowledgements
- List of symbols and abbreviations
- Part I Dark matter in cosmology
- 1 Particle dark matter
- 2 Simulations of cold dark matter haloes
- 3 Milky Way satellites
- 4 Gravitational lensing and dark matter
- 5 Dark matter at the centres of galaxies
- 6 Modified gravity as an alternative to dark matter
- Part II Candidates
- Part III Collider searches
- Part IV Direct detection
- Part V Indirect detection and astrophysical constraints
- References
- Index
3 - Milky Way satellites
Published online by Cambridge University Press: 04 August 2010
- Frontmatter
- Contents
- List of contributors
- Preface
- Acknowledgements
- List of symbols and abbreviations
- Part I Dark matter in cosmology
- 1 Particle dark matter
- 2 Simulations of cold dark matter haloes
- 3 Milky Way satellites
- 4 Gravitational lensing and dark matter
- 5 Dark matter at the centres of galaxies
- 6 Modified gravity as an alternative to dark matter
- Part II Candidates
- Part III Collider searches
- Part IV Direct detection
- Part V Indirect detection and astrophysical constraints
- References
- Index
Summary
Satellite galaxies
Historical review
Since Hubble first resolved stars in external galaxies and confirmed that these ‘island universes’ were beyond the realm of our own MilkyWay Galaxy, astronomers have sought to understand the properties of galaxies over many orders of magnitude in luminosity and distance from the Milky Way. To deal with the various morphologies of observed galaxies, Hubble proposed a classification in which galaxies are broadly identified as variations of spirals, ellipticals and irregulars. Although galaxies are observed with widely varying morphologies, the mass of most of them appears to be dominated by an unseen dark matter component, as was shown by Vera Rubin, Ken Freeman and others using measurements of gas clouds in spiral galaxies in the 1970s. Since these early studies, observations of the mass distributions of many galaxies have been studied, with results showing that the ratio of dark matter to luminous matter varies from galaxy to galaxy; the largest clusters of galaxies and the smallest known dwarf galaxies have the highest ratio of dark to luminous matter.
It is now known that even though galaxies with brightness similar to that of the Milky Way dominate the luminosity distribution of galaxies, by far the most numerous galaxies in the Universe are dwarf galaxies, which fall under Hubble's irregular category. The first recorded discovery of a dwarf galaxy came perhaps as early as the tenth century in the Persian astronomer Al-Sufi's Book of Fixed Stars.
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- Particle Dark MatterObservations, Models and Searches, pp. 38 - 55Publisher: Cambridge University PressPrint publication year: 2010
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