A sample of 11 thousand galaxies with radial velocities V _ { LG } < 3500 km/s is used to study the features of the local distribution of luminous ( stellar ) and dark matter within a sphere of radius of around 50 Mpc around us .
The average density of matter in this volume , \Omega _ { m, { loc } } = 0.08 \pm 0.02 , turns out to be much lower than the global cosmic density \Omega _ { m, { glob } } = 0.28 \pm 0.03 .
We discuss three possible explanations of this paradox : 1 ) galaxy groups and clusters are surrounded by extended dark halos , the major part of the mass of which is located outside their virial radii ; 2 ) the considered local volume of the Universe is not representative , being situated inside a giant void ; and 3 ) the bulk of matter in the Universe is not related to clusters and groups , but is rather distributed between them in the form of massive dark clumps .
Some arguments in favor of the latter assumption are presented .
Besides the two well-known inconsistencies of modern cosmological models with the observational data : the problem of missing satellites of normal galaxies and the problem of missing baryons , there arises another one—the issue of missing dark matter .