= Solution
Measurements at many source redshifts directly sample the function $H_0[1+z-E(z)]$. In principle, sufficiently many precise and well-spaced measurements can fit $H_0,\Omega_{m,0},\Omega_{{\rm DE},0},w_0,w_a$ simultaneously; a single redshift supplies only one combination and cannot. In a spatially flat two-component model, $\Omega_{m,0}+\Omega_{{\rm DE},0}=1$, reducing the number of independent parameters by one. In practice the signal accumulated over ten years is extremely small and parameter degeneracies require broad redshift coverage and complementary data.
Back to article page
