7. DARK MATTER

7.1 Historical Introduction

• Dark matter in the Galactic disk (Oort)
  
• Dark matter in the Coma cluster (Zwicky)
  
• Stability of cold disks versus bars (Ostriker &Peebles)
  
  

7.2 Observational Evidence for Dark Matter

• HI rotation curves
  
• Velocity dispersions in dSph galaxies
  
• Satellites of our Galaxy
  
• X-ray gas in galaxies and clusters: hydrostatic equilibrium of a hot gas
  
• Velocity dispersions of clusters of galaxies
  
• Gravitational lenses
  
• Large-scale velocity fields
  
  

7.3 Regularities in DM Halo Properties

• Conspiracy between luminous and dark matter to make flat V (r )
  
• Parameter correlations
  
  • Rotation curve decomposition into visible and dark matter components
    
  • Fundamental plane for dark matter halos
    
  • Evidence for baryonic compression of dark matter halos
    
  • Implications for galaxy formation
    
    

7.4 What is Dark Matter?

• MOND: Modified Newtonian Dynamics?
  
• Disk dark matter is baryonic: it dissipated
  
• Primordial nucleosynthesis constraints on baryonic dark matter
  
• Baryonic halos?
  
  • Things that won’t work: snowballs, M dwarfs, white dwarfs, neutron stars
    
  • Things that might work: brown dwarfs, black holes of mass 10^5±1
    
• Gravitational microlensing surveys
  
• Hot, warm, and cold elementary particles
  
• Constraints on neutrino dark matter from dwarf galaxies
  
• Direct detection of particle dark matter