Temporal enhancement of super-horizon curvature perturbations from decays of two curvatons and its cosmological consequences

Journal Article · Sat Oct 15 00:00:00 EDT 2011 · Physical Review. D, Particles Fields

DOI:https://doi.org/10.1103/PHYSREVD.84.083511· OSTI ID:21607870

Suyama, Teruaki ^[1]; Yokoyama, Jun'ichi ^[1]

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1. Research Center for the Early Universe (RESCEU), Graduate School of Science, University of Tokyo, Tokyo 113-0033 (Japan)

If more than one curvaton dominate the Universe at different epochs from each other, curvature perturbations can be temporarily enhanced to a value much larger than the observed one 10{sup -5}. The traces of the enhancement may be left as higher order correlation functions, that is, as non-Gaussianity, the stochastic gravitational waves that are sourced by scalar-scalar mode couplings, as well as the primordial black holes that are formed by the gravitational collapse of the enhanced curvature perturbations. We first confirm that such a temporal enhancement indeed occurs by solving the linearized perturbation equations both numerically and analytically. We then derive an analytic expression of the full-order curvature perturbation which does not rely on the frequently used sudden decay approximation and is exact on superhorizon scales. By using this analytic formula, we provide expressions of the nonlinearity parameters f{sub NL}, {tau}{sub NL} and g{sub NL}. If both two curvatons contribute to the final curvature perturbations, the strong non-Gaussianity appears in the trispectrum rather than in the bispectrum. We also find a unique consistency relation between {tau}{sub NL} and g{sub NL} without f{sub NL}. By using the second-order perturbation theory, we numerically show that the spectrum of the induced gravitational waves has a plateau corresponding to duration of the enhancement and such gravitational waves can be probed by ultimate-DECIGO and space-based atomic interferometers. We finally calculate the abundance of the primordial black holes and put a constraint on the amplitude of the enhanced curvature perturbations.

• OSTI ID: 21607870
• Journal Information: Physical Review. D, Particles Fields, Vol. 84, Issue 8; Other Information: DOI: 10.1103/PhysRevD.84.083511; (c) 2011 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); ISSN 0556-2821
• Country of Publication: United States
• Language: English

Related Subjects

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
79 ASTROPHYSICS
COSMOLOGY AND ASTRONOMY
ABUNDANCE
AMPLITUDES
APPROXIMATIONS
BLACK HOLES
CORRELATION FUNCTIONS
COUPLING
DISTURBANCES
EQUATIONS
GRAVITATIONAL COLLAPSE
GRAVITATIONAL WAVES
INTERFEROMETERS
NONLINEAR PROBLEMS
PARTICLE DECAY
PERTURBATION THEORY
SPECTRA
STOCHASTIC PROCESSES
UNIVERSE
CALCULATION METHODS
DECAY
FUNCTIONS
MEASURING INSTRUMENTS