This phenomenon results in a negative pressure in the acceleration equation, and candidates for it include quintessence and vacuum energy.
This quantity appears as a density term proportional to the scale factor raised to the power minus 3 times the quantity 1 plus w-sub-Q in the Friedmann equation. If this quantity can vary with time, it will result in density perturbations, although these are suppressed in most cosmological models. George Efstathiou at Cambridge has found evidence for it in the clustering of 250,000 galaxies, and some form of it is believed to make up about 2/3 of the critical density in lambda-CDM models. This phenomenon results in a negative pressure in the acceleration equation, and candidates for it include quintessence and vacuum energy. FTP, identify this energy term enfolded within the cosmological constant, which is believed to drive the expansion of the universe.
This quantity appears as a density term proportional to the scale factor raised to the power minus 3 times the quantity 1 plus w-sub-Q in the Friedmann equation.
dark energy