Studies based on the Magellanic stream and timing arguments in local groups give a higher value of about 0.06 h -1 . The mass density in groups of galaxies contributes about 0.16 and that in large clusters give about 0.25. The Virgo centric fall also suggests a mass density of 0.25. Two features stand out in the above estimates if they are all correct. First, there seems to be a tendency for to increase with the scale over which it is measured.
Inflation makes definite claims regarding the above situation.
Non-baryonic dark matter may be needed for a completely different reason. As discussed above, perturbations in the baryonic matter are constrained to be less than about 10 -4 at decoupling. This does not give sufficient time for these perturbations to grow into the structures we see today. The constraints on non-baryonic matter, which does not couple directly to radiation, are often less severe. A model for galaxy formation incorporating these constraints is not very easy to build, however.