Abstract
While cosmological inputs like the cosmic microwave background and the baryon-acoustic oscillations yield a clear support for the Lambda Cold Dark Matter model, the small scale (galaxies and dwarf galaxies) poses serious challenges. A way out is offered by gravitational hydrodynamics, that connects galactic dark matter with the missing baryon problem. The resulting picture puts forward that galactic halos consist of millions of Jeans clusters, each of which contains billions of Machos of Earth mass. It explains many observations that challenge LCDM. Next, the absence of CDM in the Galaxy demands a new form of non-baryonic dark matter. Weak and strong lensing by the galaxy cluster Abell 1689 can be described by quantum degenerate neutrinos of 1.5 eV mass. When non-degenerate, that is, outside centers of galaxy clusters, they behave much like cold dark matter, which explains some of the successes of the latter.
Theodorus Maria Nieuwenhuizen