2020/11/30 by Andreas Nygaard, Thomas Tram, Steen Hannestad · 48 citations
Physics and Astronomy · #Baryon acoustic oscillations #Cold dark matter #Cosmic background radiation #Cosmic microwave background #Cosmology and Gravitation Theories #Dark Matter and Cosmic Phenomena #Dark matter #Dark radiation #Massless particle #Neutrino #Particle physics theoretical and experimental studies #Planck #astro-ph.CO
paper · pdf · doi:10.1088/1475-7516/2021/05/017
published in Journal of Cosmology and Astroparticle Physics 2021(05), 017 (Institute of Physics) · 22 pages, 9 figures. Major revision after submission to JCAP. Erroneous results have been corrected and a section discussing the impact on the Hubble and $σ_8$ tensions has been added
openalex created_date 2020/11/09 · openalex publication_date 2021/05/01 · arxiv created 2021/05/12 · arxiv updated 2021/05/13 · openalex updated_date 2026/08/05
Abstract In this paper we update the constraints on the simple decaying cold dark matter (DCDM) model with dark radiation (DR) as decay product. We consider two different regimes of the lifetime, i.e. short-lived and long-lived, and use the most recent CMB data from Planck (2018) to infer new constraints on the decay parameters with which we compare the constraints inferred by the previous Planck data (2015). We hereby show that the newest CMB data constrains the fractional amount of DCDM twice as much as the previous data in the long-lived regime, leading to our current best 2σ upper bound of f dcdm < 2.44%. In the short-lived regime, we get a slightly looser 2σ upper bound of f dcdm < 13.1% compared to the previous CMB data. If we include Baryonic Acoustic Oscillations data from BOSS DR-12, the constraints in both the long-lived and the short-lived regimes relax to f dcdm < 2.62% and f dcdm < 1.49%, respectively. We also investigate how this model impacts the Hubble and σ 8 tensions, and we find that each of the decay regimes can slightly relieve a different one of the tensions. The model can thus not accommodate both tensions at once, and the improvements on each are not significant. We furthermore improve on previous work by thoroughly analysing the impacts of short-lived DCDM on the radiation density and deriving a mapping between short-lived DCDM and a correction, Δ N eff , to the effective number of massless neutrino species.