Is the Hubble Constant Scale-Dependent?

Abstract

An exact determination of the Hubble constant remains one of key problems in cosmology for almost a century. However, its modern values derived by various methods still disagree from each other by almost 10%; the greater values being obtained by measurements at the relatively small distances (e.g., by Cepheid stars as the standard candles), while the smaller values being characteristic of the methods associated with huge spatial scales (e.g., the analysis of the cosmic microwave background fluctuations). A reasonable way to resolve this puzzle is to assume that the Hubble constant is inherently scale-dependent. This idea seems to be particularly attractive in light of the latest observational results on the early-type galaxies, where the dark-matter haloes are almost absent. Therefore, an average contribution of the irregularly-distributed dark matter to the rate of the cosmological expansion should be substantially different at various spatial scales. As follows from the rough estimates, the corresponding variation of the Hubble constant can be 10% and even more, which well explains the spread in its values obtained by the various methods.