The Extragalactic Distance Scale

• Why do we need to get this right?
• Cepheid H0 determination (from Freedman etal 2001)
  
• The Distance Scale Ladder
• Important things to remember for small errors:
• magnitude error ~ fractional luminosity error
• distance error ~ 0.5 * distance modulus error
  
• Extragalactic Distance Indicators:
• Standard Candles
• Cepheids (currently only works to d=20 Mpc or so)
  
• Surface Brightness Fluctuations
• Type Ia supernovae
• Dynamical Distance Indicators
• Tully-Fisher (spirals)
• Fundamental Plane / Dn-sigma (ellipticals)
• "Physical" or "Direct" Methods
• Gravitational Lensing
• Sunyaev-Zeldovich Effect