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Gravitational waves from warm inflation in the weak dissipative regime

Orlando Luongo, Tommaso Mengoni, Paulo M. Sá

Abstract

Previous work on the gravitational-wave background generated in a two-scalar-field cosmological model, in which warm inflation and the dark sector are unified within a single framework, has shown that the resulting spectrum could be potentially detectable by planned next-generation gravitational-wave observatories. In this work, we extend this analysis to the weak dissipation regime of warm inflation, highlighting how the features of the inflationary scenario play a crucial role in the production of gravitational waves. The full gravitational-wave energy spectrum is calculated using the formalism of continuous Bogoliubov coefficients. By comparing our results with those obtained in the strong dissipation regime and with the sensitivity curves of future detectors, we find that the weak dissipation regime improves the prospects for observational detection.

Gravitational waves from warm inflation in the weak dissipative regime

Abstract

Previous work on the gravitational-wave background generated in a two-scalar-field cosmological model, in which warm inflation and the dark sector are unified within a single framework, has shown that the resulting spectrum could be potentially detectable by planned next-generation gravitational-wave observatories. In this work, we extend this analysis to the weak dissipation regime of warm inflation, highlighting how the features of the inflationary scenario play a crucial role in the production of gravitational waves. The full gravitational-wave energy spectrum is calculated using the formalism of continuous Bogoliubov coefficients. By comparing our results with those obtained in the strong dissipation regime and with the sensitivity curves of future detectors, we find that the weak dissipation regime improves the prospects for observational detection.
Paper Structure (4 sections, 18 equations, 2 figures, 1 table)

This paper contains 4 sections, 18 equations, 2 figures, 1 table.

Table of Contents

  1. Introduction
  2. The strong and weak dissipation regimes in the two-scalar-field cosmological model
  3. Gravitational-wave energy spectra
  4. Conclusions

Figures (2)

  • Figure 1: Evolution of the dissipation ratios $Q_\xi$ and $Q_\phi$, for the four scenarios under consideration. At the end of the inflationary period ($u\approx-65$), the dissipation coefficients $\Gamma_\xi$ and $\Gamma_\phi$ are exponentially suppressed, implying that soon afterward the dissipation ratios become negligible. This marks the end of the first stage of evolution.
  • Figure 2: Full gravitational-wave energy spectra for the four scenarios under consideration. The amplitude of $\Omega_{\texttt{GW}}$ increases by over an order of magnitude across the entire allowed frequency range in the weak scenario as compared to the strong one. The spectra for the strong-weak and weak-strong scenarios almost exactly coincide with the spectra for the strong and weak cases, respectively. The obtained spectra are superimposed on the sensitivity curves Schmitz:2020syl (for the repository with the sensitivity curves, see Ref. repository) of LISA, BBO, CE, ET, SKA, IPTA, and DECIGO. In the frequency bands $(10^{-9}-10^{-8})\,\hbox{Hz}$ and $(10^{-3}-1)\,\hbox{Hz}$, the gravitational waves signals are potentially detectable.