The dark matter of the Abell 1689 Galaxy Cluster is modeled by thermal, non-relativistic gravitating fermions and its galaxies and X-ray gas by isothermal distributions. A fit yields a mass of h70½(12/bar g)1/4 1.445(30) eV. A dark-matter fraction Ων=h70-3/20.1893(39) occurs for bar g = 12 degrees of freedom, i.e., for 3 families of left- plus right-handed neutrinos with masses ≈23/4GF1/2me2. Given a temperature of 0.045 K and a de Broglie length of 0.20 mm, they establish a quantum structure of several million light years across, the largest known in the Universe. The virial α-particle temperature of 9.9±1.1 keV/kB coincides with the average one of X-rays. The results are compatible with neutrino genesis, nucleosynthesis and free streaming. The neutrinos condense on the cluster at redshift z~28, thereby causing reionization of the intracluster gas without assistance of heavy stars. The baryons are poor tracers of the dark-matter density.
EPL (Europhysics Letters)
- Pub Date:
- June 2009
- General Relativity and Quantum Cosmology;
- High Energy Physics - Experiment;
- High Energy Physics - Theory
- Extended published version, 6.1 pages, 2 figures