Figure 26-23: Using Simulations to Constrain the Matter Density of the Universe Cold dark matter simulations like those in Figure 26-19 and Figure 26-20 help astronomers determine the value of the matter density parameter Ωm. These three simulations show a portion of the universe at z = 0. (a) A simulation with Ωm = 0.3 and ΩΛ = 0.7, close to the values for our universe, gives a good match to the observed distribution of filaments and voids. (b) Nearly as good a match is obtained if we keep Ωm = 0.3, but eliminate dark energy so that ΩΛ = 0. (c) If we use a larger value of Ωm, the distribution of matter in the simulation is a poor match to our universe.
(Simulation by the Virgo Supercomputing Consortium using computers based at the Computer Centre of the Max Planck Society in Garching and at the Edinburgh Parallel Computer Centre)