Production of Gravitational Waves from Preheating and Tachyonic Instabilities

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Main Authors: Alam, Khursid, Dutta, Koushik, Khan, Ahamadullah
Format: Preprint
Published: 2025
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author Alam, Khursid
Dutta, Koushik
Khan, Ahamadullah
author_facet Alam, Khursid
Dutta, Koushik
Khan, Ahamadullah
contents We analyze GW production during preheating for an $α$-attractor potential terminating in the positive-curvature regime, with energy transfer via $ϕχ^{2}$. Linear Floquet analysis and nonlinear simulations show that $ϕ$ fluctuations grow by parametric resonance, while $χ$ undergoes tachyonic bursts. The GW spectrum features two peaks: a dominant low-frequency peak from the parametric channel and a subdominant high-frequency peak from the tachyonic channel. Redshifted to today, the peak reaches $h^{2}Ω_{\rm GW}^{(0)} \sim 10^{-11}$ at $f^{(0)}_{p} \sim 10^{7}$ Hz. This multi-peak structure is a characteristic imprint of trilinear preheating in $α$-attractors.
format Preprint
id arxiv_https___arxiv_org_abs_2510_27586
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Production of Gravitational Waves from Preheating and Tachyonic Instabilities
Alam, Khursid
Dutta, Koushik
Khan, Ahamadullah
Cosmology and Nongalactic Astrophysics
General Relativity and Quantum Cosmology
High Energy Physics - Phenomenology
High Energy Physics - Theory
We analyze GW production during preheating for an $α$-attractor potential terminating in the positive-curvature regime, with energy transfer via $ϕχ^{2}$. Linear Floquet analysis and nonlinear simulations show that $ϕ$ fluctuations grow by parametric resonance, while $χ$ undergoes tachyonic bursts. The GW spectrum features two peaks: a dominant low-frequency peak from the parametric channel and a subdominant high-frequency peak from the tachyonic channel. Redshifted to today, the peak reaches $h^{2}Ω_{\rm GW}^{(0)} \sim 10^{-11}$ at $f^{(0)}_{p} \sim 10^{7}$ Hz. This multi-peak structure is a characteristic imprint of trilinear preheating in $α$-attractors.
title Production of Gravitational Waves from Preheating and Tachyonic Instabilities
topic Cosmology and Nongalactic Astrophysics
General Relativity and Quantum Cosmology
High Energy Physics - Phenomenology
High Energy Physics - Theory
url https://arxiv.org/abs/2510.27586