Constraints on Dark Energy from Supernovae, Gamma‐Ray Bursts, Acoustic Oscillations, Nucleosynthesis, Large‐Scale Structure, and the Hubble Constant

Abstract

The luminosity distance versus redshift law is now measured using supernovae and -ray bursts, and the angular size distance is measured at the surface of last scattering by the CMB and at z ¼ 0:35 by baryon acoustic oscilla-tions. In this paper, this data is fit to models for the equation of state with w ¼ À1, w ¼ constant, and w(z) ¼ w 0 þ w a (1 À a). The last model is poorly constrained by the distance data, leading to unphysical solutions where the dark energy dominates at early times unless the large-scale structure and acoustic scale constraints are modified to allow for early-time dark energy effects. A flat ÃCDM model is consistent with all the data.