Dark energy and the cosmic microwave background radiation

Area of Science:

• Cosmology
• Astrophysics

Background:

• The spatial curvature and energy density of the Universe are fundamental cosmological parameters.
• Inflation theory predicts a spatially flat Universe with energy density near critical.

Purpose of the Study:

• To constrain the Universe's spatial curvature and energy density using cosmic microwave background (CMB) anisotropy data.
• To provide evidence for dark energy independent of supernovae observations.

Main Methods:

• Analysis of current cosmic microwave background anisotropy data.
• Robustness checks involving data set editing and variation of cosmological parameters (including the cosmological constant).

Main Results:

• CMB data strongly constrain the mean spatial curvature to be near zero (spatially flat).
• The total energy density is constrained to be near critical density.
• Nonrelativistic matter density is found to be significantly less than critical density.

Conclusions:

• The findings support the prediction of inflation theory regarding spatial flatness.
• The combination of a near-critical energy density and low matter density provides independent evidence for the existence of dark energy.