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

Abstract

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 wavesmore » 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.« less

Authors:
 [1];  [1]
  1. Research Center for the Early Universe (RESCEU), Graduate School of Science, University of Tokyo, Tokyo 113-0033 (Japan)
Publication Date:
OSTI Identifier:
21607870
Resource Type:
Journal Article
Journal Name:
Physical Review. D, Particles Fields
Additional Journal Information:
Journal Volume: 84; Journal Issue: 8; Other Information: DOI: 10.1103/PhysRevD.84.083511; (c) 2011 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 0556-2821
Country of Publication:
United States
Language:
English
Subject:
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

Citation Formats

Suyama, Teruaki, Yokoyama, Jun'ichi, and Institute for the Physics and Mathematics of the Universe. Temporal enhancement of super-horizon curvature perturbations from decays of two curvatons and its cosmological consequences. United States: N. p., 2011. Web. doi:10.1103/PHYSREVD.84.083511.
Suyama, Teruaki, Yokoyama, Jun'ichi, & Institute for the Physics and Mathematics of the Universe. Temporal enhancement of super-horizon curvature perturbations from decays of two curvatons and its cosmological consequences. United States. https://doi.org/10.1103/PHYSREVD.84.083511
Suyama, Teruaki, Yokoyama, Jun'ichi, and Institute for the Physics and Mathematics of the Universe. Sat . "Temporal enhancement of super-horizon curvature perturbations from decays of two curvatons and its cosmological consequences". United States. https://doi.org/10.1103/PHYSREVD.84.083511.
@article{osti_21607870,
title = {Temporal enhancement of super-horizon curvature perturbations from decays of two curvatons and its cosmological consequences},
author = {Suyama, Teruaki and Yokoyama, Jun'ichi and Institute for the Physics and Mathematics of the Universe},
abstractNote = {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.},
doi = {10.1103/PHYSREVD.84.083511},
url = {https://www.osti.gov/biblio/21607870}, journal = {Physical Review. D, Particles Fields},
issn = {0556-2821},
number = 8,
volume = 84,
place = {United States},
year = {2011},
month = {10}
}