Reheating, multifield inflation and the fate of the primordial observables

Journal Article · Sat Sep 01 04:00:00 EDT 2012 · Journal of Cosmology and Astroparticle Physics

DOI:https://doi.org/10.1088/1475-7516/2012/09/008· OSTI ID:22279933

Leung, Godfrey; Tarrant, Ewan R.M.; Copeland, Edmund J. ^[1]

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1. School of Physics and Astronomy, University of Nottingham, University Park, Nottingham, NG7 2RD (United Kingdom)

We study the effects of perturbative reheating on the evolution of the curvature perturbation ζ, in two-field inflation models. We use numerical methods to explore the sensitivity of f{sub NL}, n{sub ζ} and r to the reheating process, and present simple qualitative arguments to explain our results. In general, if a large non-Gaussian signal exists at the start of reheating, it will remain non-zero at the end of reheating. Unless all isocurvature modes have completely decayed before the start of reheating, we find that the non-linearity parameter, f{sub NL}, can be sensitive to the reheating timescale, and that this dependence is most appreciable for 'runaway' inflationary potentials that only have a minimum in one direction. For potentials with a minimum in both directions, f{sub NL} can also be sensitive to reheating if a mild hierarchy exists between the decay rates of each field. Within the class of models studied, we find that the spectral index n{sub ζ}, is fairly insensitive to large changes in the field decay rates, indicating that n{sub ζ} is a more robust inflationary observable, unlike the non-linearity parameter f{sub NL}. Our results imply that the statistics of ζ, especially f{sub NL}, can only be reliably used to discriminate between models of two-field inflation if the physics of reheating are properly accounted for.

• OSTI ID: 22279933
• Journal Information: Journal of Cosmology and Astroparticle Physics, Journal Name: Journal of Cosmology and Astroparticle Physics Journal Issue: 09 Vol. 2012; ISSN 1475-7516
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
COSMOLOGY
DISTURBANCES
EVOLUTION
INFLATIONARY UNIVERSE
INFLATONS
POTENTIALS
SENSITIVITY
SIGNALS
STATISTICS