2007/01/10 by M. Valdes, M. Valdés, A. Ferrara +4 · 2 citations
Physics and Astronomy · #Astronomy #Astrophysics #Astrophysics and Cosmic Phenomena #Background radiation #Brightness #Brightness temperature #Dark Ages #Dark Matter and Cosmic Phenomena #Dark matter #Galaxy #Hydrogen line #Neutrino #Nuclear physics #Particle physics #Physics #Radiation #Radio Astronomy Observations and Technology #Redshift #Reionization #Sterile neutrino #astro-ph
paper · pdf · doi:10.1111/j.1365-2966.2007.11594.x
published as Mon.Not.Roy.Astron.Soc.377:245-252,2007 · 9 pages, submitted to MNRAS
arxiv created 2007/01/10 · openalex publication_date 2007/03/26 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
Beyond reionization epoch cosmic hydrogen is neutral and can be directly observed through its 21-cm line signal. If dark matter (DM) decays or annihilates, the corresponding energy input affects the hydrogen kinetic temperature and ionized fraction, and contributes to the Lyα background. The changes induced by these processes on the 21-cm signal can then be used to constrain the proposed DM candidates, among which we select the three most popular ones: (i) 25-keV decaying sterile neutrinos, (ii) 10-MeV decaying light dark matter (LDM) and (iii) 10-MeV annihilating LDM. Although we find that the DM effects are considerably smaller than found by previous studies (due to a more physical description of the energy transfer from DM to the gas), we conclude that combined observations of the 21-cm background and of its gradient should be able to put constrains at least on LDM candidates. In fact, LDM decays (annihilations) induce differential brightness temperature variations with respect to the non-decaying/annihilating DM case up to ΔδTb= 8 (22) mK at about 50 (15) MHz. In principle, this signal could be detected both by current single-dish radio telescopes and future facilities as Low Frequency Array; however, this assumes that ionospheric, interference and foreground issues can be properly taken care of.