Dirac neutrino mass from a neutrino dark matter model for the galaxy cluster Abell 1689

TL;DR

This paper models dark matter in galaxy cluster Abell 1689 as neutrinos with a mass of about 1.85 eV, proposing Dirac neutrinos as a solution to the dark matter problem and matching cluster data with cosmic observations.

Contribution

It introduces a neutrino dark matter model for galaxy clusters that explains the core and halo structure without missing baryons, suggesting neutrinos are Dirac particles with specific mass.

Findings

Neutrino mass estimated at 1.847 eV with high precision.

Model fits cluster data and cosmic dark matter fraction.

Supports Dirac neutrino hypothesis based on absence of neutrinoless double beta decay.

Abstract

The dark matter in the galaxy cluster Abell 1689 is modelled as an isothermal sphere of neutrinos. New data on the $2d$ mass density allow an accurate description of its core and halo. The model has no "missing baryon problem" and beyond $2.1$ Mpc the baryons have the cosmic mass abundance. Combination of cluster data with the cosmic dark matter fraction -- here supposed to stem from the neutrinos -- leads to a solution of the dark matter riddle by left and right handed neutrinos with mass 1.847 +/- 0.016 eV. The thus far observed absence of neutrinoless double beta decay points to (quasi-) Dirac neutrinos: uncharged electrons with different flavour and mass eigenbasis, as for quarks. Though the cosmic microwave background spectrum is matched up to some 10\% accuracy only, the case is not ruled out because the plasma phase of the early Universe may be turbulent.