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| Format: | Preprint |
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2025
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| Online Access: | https://arxiv.org/abs/2512.04240 |
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| _version_ | 1866908693588606976 |
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| author | Garcia, Marcos A. G. Verner, Sarunas |
| author_facet | Garcia, Marcos A. G. Verner, Sarunas |
| contents | We present a mechanism for gravitational wave (GW) production from isocurvature perturbations in spectator scalar fields during inflation. These energetically subdominant fields develop blue-tilted power spectra through inflationary dynamics, generating second-order scalar perturbations that source a stochastic GW background. The mechanism naturally satisfies CMB constraints at large scales while producing enhanced signals at smaller scales across a broad frequency range $10^{-20} - 1$ Hz. We perform comprehensive numerical and analytical calculations of the complete isocurvature spectrum evolution, including gravitational particle production, reheating dynamics, and scalar-induced GW generation. For spectator fields with effective masses $0.5 \lesssim m_{χ,\mathrm{eff}}/H_I$, the resulting GW energy density reaches $Ω_{\text{GW}} h^2 \sim 10^{-20}$-$10^{-12}$, accessible to pulsar timing arrays, space-based interferometers, and next-generation CMB experiments. Our analysis reveals that GW-induced constraints exceed current isocurvature bounds. We examine both unstable (curvaton-like) and stable (dark matter) spectator fields, demonstrating strong sensitivity to reheating temperature, inflaton-spectator coupling, and decay dynamics. This framework establishes isocurvature-sourced GWs as a powerful probe of early universe physics, enabling simultaneous constraints on inflationary dynamics, dark matter production, and reheating through coordinated multi-frequency GW observations. |
| format | Preprint |
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arxiv_https___arxiv_org_abs_2512_04240 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Gravitational Waves from Isocurvature Perturbations of Spectator Scalar Fields Garcia, Marcos A. G. Verner, Sarunas High Energy Physics - Phenomenology Cosmology and Nongalactic Astrophysics General Relativity and Quantum Cosmology We present a mechanism for gravitational wave (GW) production from isocurvature perturbations in spectator scalar fields during inflation. These energetically subdominant fields develop blue-tilted power spectra through inflationary dynamics, generating second-order scalar perturbations that source a stochastic GW background. The mechanism naturally satisfies CMB constraints at large scales while producing enhanced signals at smaller scales across a broad frequency range $10^{-20} - 1$ Hz. We perform comprehensive numerical and analytical calculations of the complete isocurvature spectrum evolution, including gravitational particle production, reheating dynamics, and scalar-induced GW generation. For spectator fields with effective masses $0.5 \lesssim m_{χ,\mathrm{eff}}/H_I$, the resulting GW energy density reaches $Ω_{\text{GW}} h^2 \sim 10^{-20}$-$10^{-12}$, accessible to pulsar timing arrays, space-based interferometers, and next-generation CMB experiments. Our analysis reveals that GW-induced constraints exceed current isocurvature bounds. We examine both unstable (curvaton-like) and stable (dark matter) spectator fields, demonstrating strong sensitivity to reheating temperature, inflaton-spectator coupling, and decay dynamics. This framework establishes isocurvature-sourced GWs as a powerful probe of early universe physics, enabling simultaneous constraints on inflationary dynamics, dark matter production, and reheating through coordinated multi-frequency GW observations. |
| title | Gravitational Waves from Isocurvature Perturbations of Spectator Scalar Fields |
| topic | High Energy Physics - Phenomenology Cosmology and Nongalactic Astrophysics General Relativity and Quantum Cosmology |
| url | https://arxiv.org/abs/2512.04240 |