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

The luminosity distance vs. redshift law is now measured using supernovae andgamma ray bursts, and the angular size distance is measured at the surface oflast scattering by the CMB and at z = 0.35 by baryon acoustic oscillations. Inthis paper this data is fit to models for the equation of state with w = -1, w= const, and w(z) = w_0+w_a(1-a). The last model is poorly constrained by thedistance data, leading to unphysical solutions where the dark energy dominatesat early times unless the large scale structure and acoustic scale constraintsare modified to allow for early time dark energy effects. A flat LambdaCDMmodel is consistent with all the data.Comment: 19 pages Latex with 8 Postscript figure files. A new reference and constraint, w vs w' contour plots updated. Version accepted by the the Ap