WarmSPy: a numerical study of cosmological perturbations in warm inflation

Abstract

We present WarmSPy, a numerical code in Python designed to solve for the perturbations' equations in warm inflation models and compute the corresponding scalar power spectrum at CMB horizon crossing. In models of warm inflation, a radiation bath of temperature $T$ during inflation induces a dissipation (friction) rate of strength $Q\propto T^c/{\varphi }^m$ in the equation of motion for the inflaton field $\varphi$. While for a temperature-independent dissipation rate ($c=0$) an analytic expression for the scalar power spectrum exists, in the case of a non-zero value for $c$ the set of equations can only be solved numerically. For $c>0$ ($c<0$), the coupling between the perturbations in the inflaton field and radiation induces a growing (decaying) mode in the scalar perturbations, generally parameterized by a multiplicative function $G(Q)$ which we refer to as the scalar dissipation function. Using WarmSPy, we provide an analytic fit for $G(Q)$ for the cases of $c=\{3,1,-1\}$, corresponding to three cases that have been realized in physical models. Compared to previous literature results, our fits are more robust and valid over a broader range of dissipation strengths $Q\in [10^{-7},10^4]$. Additionally, for the first time, we numerically assess the stability of the scalar dissipation function against various model parameters, inflationary histories as well as the effects of metric perturbations. As a whole, the results do not depend appreciably on most of the parameters in the analysis, except for the dissipation index $c$, providing evidence for the universal behaviour of the scalar dissipation function $G(Q)$.

37 pages, 8 figures, 1 table, Replacement due to typo on table 1 and figure 2

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Cited by in corpus (23)

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• A generalized method of constraining Warm Inflation with CMB data
• WI2easy: warm inflation dynamics made easy
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• Warm inflation with a heavy QCD axion
• Evolution of coupled scalar perturbations through smooth reheating. I. Dissipative regime
• On Sphaleron Heating in the Presence of Fermions
• Warming up the Fibres
• A comparative analysis of dissipation coefficients in warm inflation
• Warm multi natural inflation
• Reassessing constant-roll Warm Inflation
• Purely gravitational dark matter production in warm inflation
• Evolution of coupled scalar perturbations through smooth reheating. II. Thermal fluctuation regime
• Defying eternal inflation in warm inflation with a negative running
• Witten-O'Raifeartaigh potential revisited in the context of Warm Inflation
• Warm inflation in Weyl geometric gravity
• Primordial non-Gaussianity in noncanonical warm inflation with nonminimal derivative coupling
• AliCPT Sensitivity to Cosmic Reheating
• Dynamics of potential-free warm $\mathbf{k}$-inflation with nonminimal derivative coupling
• Classical equipartition dynamics between axions and non-Abelian gauge fields
• Scalaron-driven Dark Matter during Warm Inflation via UV Freeze--in