Precision estimate of cosmological and particle parameters in the decaying-dark-matter hypothesis

D. W. Sciama
Phys. Rev. Lett. 65, 2839 – Published 3 December 1990
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Abstract

I have recently proposed that both H i regions of the Galaxy and Lyman-α clouds are mainly ionized by decaying dark matter. Here I point out that to avoid an excessive metagalactic ionizing flux F, the energy Eγ of the decay photons must be severely constrained. It then follows that the mass m1 and lifetime τ of the decaying particles, the flux F, the density ρ and age tU of the Universe, Ω (=ρ/ρcrit), and the Hubble constant H also have to be severely constrained. The validity of our theory requires that Eγ=14.4±0.5 eV, m1=28.9±1.1 eV, τ=(2+1)×1023 sec, F=(3.8±2.2)×105 cm2 sec1, ρ=(6.14±0.26×1030 g cm3, tU∼1.2×1010yr, Ω∼1, and H=55±1 km sec1 Mpc1.

  • Received 15 March 1990

DOI:https://doi.org/10.1103/PhysRevLett.65.2839

©1990 American Physical Society

Authors & Affiliations

D. W. Sciama

  • International School for Advanced Studies, I-34 014 Trieste, Italy
  • International Centre for Theoretical Physics, I-34 100 Trieste, Italy
  • Department of Astrophysics, University of Oxford, Oxford OX1 3RQ, Oxfordshire, United Kingdom
  • Institute of Astronomy, University of Cambridge, Cambridgeshire, United Kingdom

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Vol. 65, Iss. 23 — 3 December 1990

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