2020/09/30 by Catarina Cosme, Tommi Tenkanen · 1 citation
Physics and Astronomy · #Astrophysics #Black Holes and Theoretical Physics #Classical mechanics #Cosmology #Cosmology and Gravitation Theories #Dark Matter and Cosmic Phenomena #Dark energy #Dark matter #Inflation (cosmology) #Lambda-CDM model #Perturbation (astronomy) #Physics #Quantum mechanics #Scalar field #Theoretical physics #astro-ph.CO #gr-qc #hep-ph
paper · pdf · doi:10.1103/physrevd.102.123534
published as Phys. Rev. D 102, 123534 (2020) · 22 pages, 10 figures, references added, matches PRD published version
openalex publication_date 2020/12/22 · arxiv created 2021/01/05 · arxiv updated 2021/01/07 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
It has been shown that the observed dark matter (DM) abundance can be produced by amplification of quantum fluctuations of an energetically subdominant scalar field during inflation. In this paper, we study the robustness of this ``spectator dark matter'' scenario to changes in the expansion rate of the early Universe. Compared to the standard radiation-dominated (RD) scenario, two aspects will change: the DM energy density evolves differently as a function of time, and also the DM isocurvature perturbation spectrum will be different from the result in the RD case. These can impose sizeable changes to the values of model parameters which allow the field to constitute all DM while simultaneously satisfying all observational constraints. We study both free and self-interacting DM in scenarios with nonstandard expansion and quantify the changes to the cases with a standard cosmological history. We also discuss testability of the scenario through primordial DM isocurvature and non-Gaussianity.