Volume 86, Number 5, June 2009
Article Number 59001
Number of page(s) 6
Section Geophysics, Astronomy and Astrophysics
Published online 29 May 2009
EPL, 86 (2009) 59001
DOI: 10.1209/0295-5075/86/59001

Do non-relativistic neutrinos constitute the dark matter?

Th. M. Nieuwenhuizen

Institute for Theoretical Physics, University of Amsterdam - Valckenierstraat 65, 1018 XE Amsterdam, The Netherlands, EU

received on 13 May 2009; accepted in final form by R. A. Treumann on 18 May 2009; published June 2009
published online 29 May 2009

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 $h_{70}^{1/2}(12/{\bar g})^{1/4} 1.445(30)$ eV. A dark-matter fraction $\Omega _{\nu}=h_{70}^{- 3/2}0.1893(39)$ occurs for ${\bar g}$ = 12 degrees of freedom, i.e., for 3 families of left- plus right-handed neutrinos with masses $\approx 2^{3/4}G_{F}^{1/2}m_{e}^{2}$. 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 $\alpha $-particle temperature of 9.9$\pm$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.

95.35.+d - Dark matter (stellar, interstellar, galactic, and cosmological).
98.65.-r - Galaxy groups, clusters, and superclusters; large scale structure of the Universe.
14.60.St - Non-standard-model neutrinos, right-handed neutrinos, etc..

© EPLA 2009