Intergalactic medium heating by dark matter

Abstract

We derive the evolution of the energy deposition in the intergalactic medium (IGM) by dark matter (DM) decays/annihilations for both sterile neutrinos and light dark matter (LDM) particles. At z > 200 sterile neutrinos transfer a fraction f_abs~0.5 of their rest mass energy into the IGM; at lower redshifts this fraction becomes <~ 0.3 depending on the particle mass. The LDM particles can decay or annihilate. In both cases f_abs~0.4-0.9 at high (> 300) redshift, dropping to ~0.1 below z=100. These results indicate that the impact of DM decays/annihilations on the IGM thermal and ionization history is less important than previously thought. We find that sterile neutrinos (LDM) decays are able to increase the IGM temperature by z=5 at most up to 4K (100K), about 50-200 times less than predicted by estimates based on the assumption of complete energy transfer to the gas.

13 pages, 7 figures; MNRAS, in press; matches the published version

References in corpus (7)

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• Impact of dark matter decays and annihilations on reionization
• Relic keV sterile neutrinos and reionization
• Direct X-ray Constraints on Sterile Neutrino Warm Dark Matter
• Constraints on Sterile Neutrino Dark Matter
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• How Dark Matter Reionized The Universe
• Impact of Dark Matter Annihilation on the High-Redshift Intergalactic Medium
• Dark stars: Implications and constraints from cosmic reionization and extragalactic background radiation
• MeV Right-handed Neutrinos and Dark Matter
• Neutralino Annihilations and the Gas Temperature in the Dark Ages
• Cosmic constraints rule out s-wave annihilation of light dark matter