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 High-Z, Supernova Cosmology figures
  • combined data figure
  • recent data: SNLS team Lambda vs matter (Sullivan et al 2011)
    Pan-STARRS Omega_Lambda vs Omega_matter (Rest et al 2013)
• Ignorance parameterized: dark energy
  • limits on dark energy density, evolution
  • analysis including SDSS

Dark Energy

• Ignorance parameterized
  • from Kessler et al 2009: w vs matter
  • from Hicken et al 2009: density vs w
  • 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