How Dark Matter Reionized The Universe

Abstract

Although empirical evidence indicates that that the universe's gas had become ionized by redshift z ~ 6, the mechanism by which this transition occurred remains unclear. In this article, we explore the possibility that dark matter annihilations may have played the dominant role in this process. Energetic electrons produced in these annihilations can scatter with the cosmic microwave background to generate relatively low energy gamma rays, which ionize and heat gas far more efficiently than higher energy prompt photons. In contrast to previous studies, we find that viable dark matter candidates with electroweak scale masses can naturally provide the dominant contribution to the reionization of the universe. Intriguingly, we find that dark matter candidates capable of producing the recent cosmic ray excesses observed by PAMELA and/or ATIC are also predicted to lead to the full reionization of the universe by z ~ 6.

10 pages, 6 figures; error in figure 2 corrected, conclusions unchanged

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• A Theory of Dark Matter
• Measurement of the Cosmic Ray e+ plus e- spectrum from 20 GeV to 1 TeV with the Fermi Large Area Telescope
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• Impact of dark matter decays and annihilations on reionization
• Dark matter interpretation of recent electron and positron data
• Contraints on radiative dark-matter decay from the cosmic microwave background
• The impacts of dark matter particle annihilation on recombination and the anisotropies of the cosmic microwave background
• The Physics and Early History of the Intergalactic Medium
• The impact of dark matter decays and annihilations on the formation of the first structures
• Intergalactic medium heating by dark matter
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Cited by in corpus (8)

• Galaxy UV-luminosity function and reionization constraints on axion dark matter
• Constraints on Dark Matter annihilations from reionization and heating of the intergalactic gas
• Relative Role of Stars and Quasars in Cosmic Reionization
• Strong Optimized Conservative Fermi-LAT Constraints on Dark Matter Models from the Inclusive Photon Spectrum
• Heating and Ionization of the Primordial Intergalactic Medium by High Mass X-ray Binaries
• Cosmic reionization by primordial cosmic rays
• The Hydrogen Mixing Portal, Its Origins, and Its Cosmological Effects
• Dark Matter Energy Deposition and Production from the Table-Top to the Cosmos