Nonthermal neutrino-like hot dark matter in light of the tension
Résumé
The prediction of —where is the root mean square of matter fluctuations on an scale—once calibrated on Planck cosmic microwave background data is lower than its direct estimate by a number of weak lensing surveys. In this paper, we explore the possibility that the “ tension” is due to a fractional contribution of nonthermal hot dark matter (HDM) to the energy density of the Universe leading to a power suppression at small scales in the matter power spectrum. Any HDM model can be characterized by its effective mass and its contribution to the relativistic degrees of freedom at cosmic microwave background decoupling . Taking the specific example of a sterile particle produced from the decay of the inflaton during an early matter-dominated era, we find that the tension can be reduced below from Planck data only, but it does not favor a nonzero . In combination with a measurement of from , the tension would hint at the existence of a particle of mass with a contribution to . However, Pantheon and BOSS data restricts the particle mass to and contribution to . We discuss implications of our results for other canonical nonthermal HDM models—the Dodelson-Widrow model and a hidden sector model of a thermal sterile particle with a different temperature. We report competitive results on such hidden sector temperature that might have interesting implications for particle physics model building, in particular connecting the tension to the longstanding short baseline oscillation anomaly.
Mots clés
matter: power spectrum
matter: fluctuation
cosmic background radiation: decoupling
energy: density
inflaton: decay
satellite: Planck
dark matter: hidden sector
dark matter: density
tension
sterile
cosmological model: parameter space
calibration
suppression
oscillation
fractional
buildings
thermal
anomaly