Non-Gaussian isocurvature perturbations in dark radiation

Journal Article · Sun Jul 01 04:00:00 EDT 2012 · Journal of Cosmology and Astroparticle Physics

DOI:https://doi.org/10.1088/1475-7516/2012/07/037· OSTI ID:22279846

Kawakami, Etsuko; Kawasaki, Masahiro; Miyamoto, Koichi ^[1]; Nakayama, Kazunori ^[2]; Sekiguchi, Toyokazu ^[3]

---

1. Institute for Cosmic Ray Research, University of Tokyo, Kashiwa 277-8582 (Japan)
2. Institute for the Physics and Mathematics of the Universe, University of Tokyo, Kashiwa 277-8568 (Japan)
3. Department of Physics and Astrophysics, Nagoya University, Nagoya 464-8602 (Japan)

We study non-Gaussian properties of the isocurvature perturbations in the dark radiation, which consists of the active neutrinos and extra light species, if exist. We first derive expressions for the bispectra of primordial perturbations which are mixtures of curvature and dark radiation isocurvature perturbations. We also discuss CMB bispectra produced in our model and forecast CMB constraints on the non-linearity parameters based on the Fisher matrix analysis. Some concrete particle physics motivated models are presented in which large isocurvature perturbations in extra light species and/or the neutrino density isocurvature perturbations as well as their non-Gaussianities may be generated. Thus detections of non-Gaussianity in the dark radiation isocurvature perturbation will give us an opportunity to identify the origin of extra light species and lepton asymmetry.

• OSTI ID: 22279846
• Journal Information: Journal of Cosmology and Astroparticle Physics, Journal Name: Journal of Cosmology and Astroparticle Physics Journal Issue: 07 Vol. 2012; ISSN 1475-7516
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
ASTROPHYSICS
ASYMMETRY
COSMOLOGY
DENSITY
DISTURBANCES
NEUTRINOS
RELICT RADIATION