DARK MATTER DECAY AND THE IONIZATION OF H-I REGIONS IN THE GALAXY

It is argued that the observed constancy of the free electron density in H I regions near the Sun, and its relatively large scale height of ∼900 pc, can be naturally explained if dark matter in the Galaxy is producing hydrogen-ionizing photons on a time scale ∼1.5 × 1023 s. This model leads to a variety of other consequences in astronomy and cosmology, some of which are already supported by observation. These consequences include a well-defined rotation curve for the Galaxy, a strong flattering of its dark halo, and, if the particles are neutrino-like, well-defined values for the energy of the photons (13.8 ± 0.2 eV), for the rest mass of the particles (27.7 ± 0.5 eV), for the mean density of the universe (5.94 ± 0.24 × 10-30 g cm-3) and, if this density is critical, for the age of the universe (1.2 × 1010 yr) and for the Hubble constant (54.5 ± 1 km s-1 Mpc-1).