A Better Candidate for Dark Matter is Cosmic Plasma

In the Lambda CDM cosmological model, based on observations of supernovae Ia, the cosmic dark energy density is assumed to be Omega(Lambda) similar to 0.70 and the gravitational mass density is assumed to be Omega(m) similar to 0.30. Based on the assumption that the observed cosmic microwave background (CMB) is a thermal relic of the early hot universe, the cosmic plasma density should be small, i.e., Omega(b) similar to 0.05 (otherwise the Sunyaev-Zeldovich effect of the cosmic plasma would ruin the observed CMB's perfect blackbody spectrum). To fill the gap between Omega(m) and Omega(b), non-baryonic dark matter Omega(c) similar to 0.25 is introduced into the Lambda CDM model. If the CMB is the result of a partial thermal equilibrium between cosmic radiation and cosmic plasma, then the observed perfect blackbody spectrum of the CMB can coexist with cosmic plasma. In this case, it is not necessary to introduce non-baryonic cold dark matter into cosmological models. A better candidate for dark matter is the cosmic plasma.