Dark Radiation from Modulated Reheating

Abstract

We show that the modulated reheating mechanism can naturally account for dark radiation, whose existence is hinted by recent observations of the cosmic microwave background radiation and the primordial Helium abundance. In this mechanism, the inflaton decay rate depends on a light modulus which acquires almost scale-invariant quantum fluctuations during inflation. We find that the light modulus is generically produced by the inflaton decay and therefore a prime candidate for the dark radiation. Interestingly, an almost scale-invariant power spectrum predicted in the modulated reheating mechanism gives a better fit to the observation in the presence of the extra radiation. We discuss the production mechanism of the light modulus in detail taking account of its associated isocurvature fluctuations. We also consider a case where the modulus becomes the dominant component of dark matter.

16 pages; v2: added references and Appendix B; v3: published in JCAP

References in corpus (7)

• Non-Gaussianity in the modulated reheating scenario
• Sterile neutrinos with eV masses in cosmology -- how disfavoured exactly?
• Primordial Curvature Fluctuation and Its Non-Gaussianity in Models with Modulated Reheating
• The Case for Dark Radiation
• Signatures of a hidden cosmic microwave background
• A theory of extra radiation in the Universe
• Probing the Effective Number of Neutrino Species with Cosmic Microwave Background

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