  One of hot topics in the last years is a systematic discrepancy in the
determination of Hubble parameter by various methods. Namely, the values
derived "directly" from the distance scale based on Cepheids and
supernovae--and referring to the relatively "local" part of the Universe--are
about 10% greater than the ones following from the analysis of the cosmic
microwave background (CMB) radiation, which refers to the "global" scales. The
most popular interpretation of this discord, widely discussed nowadays, is
variation of the dark-energy equation-of-state parameter w. However, there
might be a much simpler explanation, following from the recent observations of
the rotation curves in the high-redshift galaxies. Namely, it was found that
they have much smaller dark-matter halos than galaxies in the vicinity of us
[Genzel, et al. Nature 543 (2017), 397]. Since both the dark and luminous
matter possess the same dust-like equation of state and, therefore, their
average cosmological densities evolve by the same way, our local neighborhood
is not quite typical but rather overfilled with the dark matter. Then, the
local value of the Hubble constant should be greater than the global one.
Roughly speaking, a twofold excess of the dark matter in our local Universe
would give just the above-mentioned 10% increase in the value of Hubble
parameter.
