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
5 - Dark matter at the centres of galaxies
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
Dark matter haloes formed in ∧CDM cosmologies exhibit a characteristic dependence of density on distance from the centre (Chapter 2). Early studies [721; 1501] established ρDM ∼ r−3 or r−4 at large radii and ρDM ∼ r−1 inside the virial radius. On still smaller scales, the form of ρDM(r) was little more than an ansatz since the relevant scales were barely resolved in the N-body simulations. A debate ensued as to whether the profiles were indeed universal and, if so, what power of the radius described the dark matter density in the limit r → 0. Subsequent studies found central profiles both steeper [666; 940; 1247; 1471] and shallower [1431; 1503; 1504] than r−1.
The focus of this chapter is the dark matter distribution on sub-parsec scales. At these radii, the gravitational force in many galaxies is known to be dominated by the observed baryonic components (stellar bulge, nuclear star cluster) and by the supermassive black hole. Dark matter densities at these radii are barely constrained observationally; however, they could plausibly be orders of magnitude higher than the local value at the solar circle (∼10−2M⊙ pc−3), owing both to the special location at the centre of the halo and to interactions between dark matter and baryons during and after formation of the galaxy. High dark matter densities make the centres of galaxies preferred targets for indirect detection studies, in which secondary particles and photons from the annihilation or decay of supersymmetric dark matter particles are detected on the Earth (Chapter 24).
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- Particle Dark MatterObservations, Models and Searches, pp. 83 - 98Publisher: Cambridge University PressPrint publication year: 2010
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