Combined Evidence for Dark Energy

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© Supernova Cosmology Project, Lawrence Berkeley National Laboratory.

The two primary lines of evidence for dark energy are the accelerated expansion of the universe measured by supernova surveys and the discrepancy between the geometry and amount of matter in the universe measured by the CMB. The plot above, with on the vertical axis and on the horizontal axis, compares the results of these two measurements. The broad orange line shows values of and that are consistent with the geometry and amount of matter allowed by the CMB measurement. The blue ellipses show values consistent with the supernova measurement, with the darker shades of blue corresponding to more likely values. The green line shows the result of another set of measurements of galaxy clusters. All three measurements are consistent—the orange, blue, and green parts of the graph meet in a single point. The gray ellipses show the values of and most consistent with all of the measurements, which we take as a sign that the picture we are developing for a universe filled with dark energy is a reliable one. (Unit: 11)