Effect of background evolution on the curvaton non-Gaussianity

Journal Article · Tue Dec 01 04:00:00 EST 2009 · Journal of Cosmology and Astroparticle Physics

DOI:https://doi.org/10.1088/1475-7516/2009/12/001· OSTI ID:22273110

Enqvist, Kari ^[1]; Takahashi, Tomo ^[2]

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1. Helsinki Institute of Physics, University of Helsinki, PO Box 64, FIN-00014 (Finland)
2. Department of Physics, Saga University, Saga 840-8502 (Japan)

We investigate how the background evolution affects the curvature perturbations generated by the curvaton, assuming a curvaton potential that may deviate slightly from the quadratic one, and parameterizing the background fluid density as ρ∝a{sup −α}, where a is the scale factor, and α depends on the background fluid. It turns out that the more there is deviation from the quadratic case, the more pronounced is the dependence of the curvature perturbation on α. We also show that the background can have a significant effect on the nonlinearity parameters f{sub NL} and g{sub NL}. As an example, if at the onset of the curvaton oscillation there is a dimension 6 contribution to the potential at 5 % level and the energy fraction of the curvaton to the total one at the time of its decay is at 1%, we find variations Δf{sub NL} ∼ O(10) and Δg{sub NL} ∼ O(10{sup 4}) between matter and radiation dominated backgrounds. Moreover, we demonstrate that there is a relation between f{sub NL} and g{sub NL} that can be used to probe the form of the curvaton potential and the equation of state of the background fluid.

• OSTI ID: 22273110
• Journal Information: Journal of Cosmology and Astroparticle Physics, Journal Name: Journal of Cosmology and Astroparticle Physics Journal Issue: 12 Vol. 2009; ISSN 1475-7516
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
ASTROPHYSICS
COSMOLOGY
DISTURBANCES
EQUATIONS OF STATE
NONLINEAR PROBLEMS
OSCILLATIONS
POSTULATED PARTICLES
POTENTIALS
PROBES
VARIATIONS