Infrared Behavior of Induced Gravitational Waves from Isocurvature Perturbations

2025/01/17 by Chang Han, Han, Chang, Zu-Cheng Chen +5 · 1 citation
Engineering · #Calibration and Measurement Techniques #Cosmology and Nongalactic Astrophysics (astro-ph.CO) #FOS: Physical sciences #General Relativity and Quantum Cosmology (gr-qc) #Geophysics and Sensor Technology

paper · pdf · doi:10.48550/arxiv.2501.09939

openalex publication_date 2025/01/17 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28

Abstract

Induced gravitational waves provide a powerful probe of primordial perturbations in the early universe through their distinctive spectral properties. We analyze the spectral energy density Ω_GW of gravitational waves induced by isocurvature scalar perturbations. In the infrared regime, we find that the spectral slope n_GW ≡ d lnΩ_GW/dln k takes the log-dependent form 3-4/ ln (k_*² / 6k²), where k_* represents the effective peak scale of the primordial scalar power spectrum. This characteristic behavior differs markedly from that of adiabatic-induced gravitational waves, establishing a robust observational discriminant between isocurvature and adiabatic primordial perturbation modes.

Cited by

• Scalar-induced gravitational waves with non-Gaussianity up to all orders

Related

• Induced gravitational waves as a probe of thermal history of the universe
• Gauge Dependence of Gravitational Waves Induced by Primordial Isocurvature Fluctuations
• The Power Spectrum Of Gravitational Waves in Anisotropic Universe (Bianchi type--I)
• Cosmological gravitational wave background from primordial density perturbations
• Gravitational waves and the cosmological equation of state