Acceleration in a FLRW Universe

• general considerations:
  • pressure large and negative
  • strong energy condition violated
• a Cosmological Constant?
  • a colorful but checkered past: Einstein (1917), Lemaitre (1931)
  • early figures: High-Z, Supernova Cosmology Hubble diagram Matter-Lambda (Knop+ 2003), combined data, figure
  • Riess (2004): Hubble diagram
  • recent data: Dark Energy Survey luminosity distance, Matter-Lambda (Macaulay+ 2019); SNLS team Lambda vs matter (Sullivan et al 2011)
    Pan-STARRS Omega_Lambda vs Omega_matter (Scolnic+ 2018)
    w vs matter (Betoule+ 2014)
• Ignorance parameterized: dark energy
  • limits on dark energy density, evolution
  • analysis including SDSS

Dark Energy

• Ignorance parameterized
  • from Scolnic+ 2018: w₀ vs matter and w₁ vs w₀
  • from Kowalski et al 2008: w evolution,
  w vs matter, w₀ vs w_a (Betoule+ 2014)
• Coincidences: cosmic epochs in perspective
• Dark energy as a field