Cosmology
AdvancedIOAA 2008 | Bandung, Indonesia | TH S5 | 20 pt

13.3 | Dark matter versus vacuum energy at recombination

The CMB temperature is currently 2.73 K2.73\,\mathrm K and its emission redshift is zCMB=1100z_{\rm CMB}=1100. Present densities are ρDE,0=7.1×10−30 g cm−3\rho_{\rm DE,0}=7.1\times10^{-30}\,\mathrm{g\,cm^{-3}}, ρDM,0=2.4×10−30 g cm−3\rho_{\rm DM,0}=2.4\times10^{-30}\,\mathrm{g\,cm^{-3}}, and ρNM,0=0.5×10−30 g cm−3\rho_{\rm NM,0}=0.5\times10^{-30}\,\mathrm{g\,cm^{-3}}.

What was the ratio of dark matter density to dark energy density when the CMB was emitted? Assume dark energy is vacuum energy.

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