Gravitational waves from warm inflation in the weak dissipative regime

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.

💡 Research Summary

**
In this paper the authors investigate the primordial gravitational‑wave (GW) background generated in a unified two‑scalar‑field cosmology that simultaneously accounts for warm inflation, dark matter and dark energy. The model, originally introduced in earlier work, contains an inflaton field ξ and a dark‑energy field ϕ coupled through non‑minimal exponential factors e^{ακϕ} and e^{βκϕ} in the kinetic and potential terms. During the inflationary epoch the inflaton dissipates energy into a pre‑existing thermal bath; this dissipation is described phenomenologically by coefficients Γ_ξ and Γ_ϕ that depend on the temperature T as Γ∝T^{p} (for T≥T_E) or Γ∝exp