Logo
ScienceStack
Table of Contents
Fetching ...
Sign In

Non-gaussianity in fluctuations from warm inflation

Ian G Moss, Chun Xiong

TL;DR

The paper investigates non-gaussianity in density fluctuations within the strong warm inflation framework, where a radiation bath dominates inflaton dynamics and thermal fluctuations source perturbations. By modeling inflaton fluctuations with a Langevin equation and solving for the power spectrum and bispectrum under large $\nu=\Gamma/(2H)$, the authors derive a curvature bispectrum $B_\zeta$ with a dominant angular- and scale-dependent term governed by a function $L(r)$, where $r=\Gamma/(3H)$. They find that non-gaussianity can be sizable (quantified by $f_{NL}$) and exhibit a distinctive $l=1$ angular dependence, offering a practical observational signature for Planck-scale CMB analysis. The results imply that strong warm inflation could be tested or constrained by primordial non-gaussianity, providing a potential discriminator from other early-Universe scenarios such as the curvaton model.

Abstract

The scalar mode density perturbations in a the warm inflationary scenario are analysed with a view to predicting the amount of non-gaussianity produced by this scenario. The analysis assumes that the inflaton evolution is strongly damped by the radiation, with damping terms that are temperature independent. Entropy fluctuations during warm inflation play a crucial role in generating non-gaussianity and result in a distinctive signal which should be observable by the Planck satellite.

Non-gaussianity in fluctuations from warm inflation

TL;DR

The paper investigates non-gaussianity in density fluctuations within the strong warm inflation framework, where a radiation bath dominates inflaton dynamics and thermal fluctuations source perturbations. By modeling inflaton fluctuations with a Langevin equation and solving for the power spectrum and bispectrum under large , the authors derive a curvature bispectrum with a dominant angular- and scale-dependent term governed by a function , where . They find that non-gaussianity can be sizable (quantified by ) and exhibit a distinctive angular dependence, offering a practical observational signature for Planck-scale CMB analysis. The results imply that strong warm inflation could be tested or constrained by primordial non-gaussianity, providing a potential discriminator from other early-Universe scenarios such as the curvaton model.

Abstract

The scalar mode density perturbations in a the warm inflationary scenario are analysed with a view to predicting the amount of non-gaussianity produced by this scenario. The analysis assumes that the inflaton evolution is strongly damped by the radiation, with damping terms that are temperature independent. Entropy fluctuations during warm inflation play a crucial role in generating non-gaussianity and result in a distinctive signal which should be observable by the Planck satellite.

Paper Structure

This paper contains 9 sections, 90 equations, 2 figures.

Table of Contents

  1. introduction
  2. warm inflation
  3. inflaton fluctuations
  4. Inflaton power spectrum
  5. Inflaton bispectrum
  6. Density fluctuations
  7. conclusion
  8. First order cosmological perturbations
  9. Integrals

Figures (2)

  • Figure 1: The function $L(r)$ determines the size of the non-gaussianity. The upper curve is a numerical calculation and the lower an asymptotic approximation (\ref{['Ldef']}) valid for large $r$. A log-linear fit eq. (\ref{['logfit']}) is also shown.
  • Figure 2: This contour plot shows the momentum dependence of $f_{NL}^v$. The momentum $k_3$ is held fixed and placed along the $x-$ axis, whilst $k_2$ and $k_3$ are allowed to vary over the boxed region. The contour values must be multiplied by $15L(r)$ to obtain $f_{NL}^v$.