Lecture 19

BBN: Theory vs Observations

• Predictions: Schramm plot (Cyburt, Fields, & Olive 2003)
• Concordance

BBN: Implications

• baryon density
• dark matter: two kinds!
  • baryonic dark matter: e.g., hot gas in collapsed structures and intergalactic gas; MACHOs (well, probably not MACHOs)
  • non-baryonic dark matter

BBN in Light of the CMB

• Overview: BBN+CMB Schramm plot
• Standard BBN: Light element CMB predictions vs observations (CFO 2003)

BBN: Beyond the Standard Model

• Standard BBN assumptions
• Neutrino counting:
  • light element sensitivity to neutrino number
    
  • constraints on neutrino number from helium-4 and/or deuterium