Gravitational waves induced by matter isocurvature in general cosmologies
arXiv:2509.02122 · doi:10.1088/1475-7516/2025/12/017
Abstract
The expansion history and content of the Universe between the end of inflation and the onset of Big Bang Nucleosynthesis is mostly unknown. In this paper, we study gravitational waves (GWs) induced by matter isocurvature fluctuations in a generic perfect fluid background as a novel probe of the physics of the very early Universe. We analytically compute the induced GW kernel and analyze the spectral GW energy density for a sharply peaked isocurvature power spectrum. We show that the spectral shape of the GW signal is sensitive to the equation of state parameter of the perfect fluid dominating the early Universe after inflation. We find that the GW amplitude is enhanced for a soft equation of state. Our framework can be applied to dark matter isocurvature and models leading to early matter-dominated eras, such as primordial black holes and cosmological solitons.
arXiv comment18 pages + appendices, 6 figures; v2: matches published version
References in corpus (63)
- Planck 2018 results. X. Constraints on inflation
- Generating the curvature perturbation without an inflaton
- Gravitational Wave Spectrum Induced by Primordial Scalar Perturbations
- The cosmological gravitational wave background from primordial density perturbations
- Cosmological perturbations
- Quintessential inflation
- Primordial Black Holes
- MeV-scale Reheating Temperature and Thermalization of Neutrino Background
- Reheating in Inflationary Cosmology: Theory and Applications
- Semianalytic Calculation of Gravitational Wave Spectrum Nonlinearly Induced from Primordial Curvature Perturbations
- What is the lowest possible reheating temperature?
- Nonperturbative Dynamics Of Reheating After Inflation: A Review
- Cosmological Constraints on Late-time Entropy Production
- MeV-scale reheating temperature and thermalization of oscillating neutrinos by radiative and hadronic decays of massive particles
- Deflationary Universe Scenario
- General Relativistic Dynamics of Irrotational Dust: Cosmological Implications
- Oscillons After Inflation
- The First Three Seconds: a Review of Possible Expansion Histories of the Early Universe
- Cosmic Conundra Explained by Thermal History and Primordial Black Holes
- Gravitational waves from a universe filled with primordial black holes
- Electroweak Baryogenesis and the Expansion Rate of the Universe
- Universal infrared scaling of gravitational wave background spectra
- The Equation of State and Duration to Radiation Domination After Inflation
- Isocurvature Perturbations in Multiple Inflationary Models
- Primordial Black Holes from Sound Speed Resonance during Inflation
- Gravitational Wave Production right after a Primordial Black Hole Evaporation
- Reheating and Post-inflationary Production of Dark Matter
- Induced gravitational waves in a general cosmological background
- Induced gravitational waves as a probe of thermal history of the universe
- Gravitational waves from an early matter era
- Gravitational Waves Induced by Scalar Perturbations during a Gradual Transition from an Early Matter Era to the Radiation Era
- Unified treatment of cosmological perturbations from super-horizon to small scales
- Observable induced gravitational waves from an early matter phase
- Exploring Evaporating Primordial Black Holes with Gravitational Waves
- Primordial black holes from sound speed resonance in the inflaton-curvaton mixed scenario
- CMB spectral distortions from small-scale isocurvature fluctuations
- Unification of inflation and dark energy {\it à la} quintessential inflation
- Primordial Black Holes
- Decoding the phases of early and late time reheating through imprints on primordial gravitational waves
- Axion isocurvature fluctuations with extremely blue spectrum
- Dark Matter Production in an Early Matter Dominated Era
- Gravitational waves from dark matter isocurvature
- Generation of gravitational waves during early structure formation between cosmic inflation and reheating
- WIMPs, FIMPs, and Inflaton phenomenology via reheating, CMB and
- Dark Matter Production Mechanisms with a Non-Thermal Cosmological History - A Classification
- Gravitational Waves from Density Perturbations in an Early Matter Domination Era
- Primordial black holes and gravitational waves in nonstandard cosmologies
- Exploring the Spectral Shape of Gravitational Waves Induced by Primordial Scalar Perturbations and Connection with the Primordial Black Hole Scenarios
- Enhanced Gravitational Waves from Inflaton Oscillons
- The Maximal Amount of Gravitational Waves in the Curvaton Scenario
- Accounting for the time evolution of the equation of state parameter during reheating
- Expansion history-dependent oscillations in the scalar-induced gravitational wave background
- Primordial Black Holes from CDM Isocurvature Perturbations
- Memory burden effect mimics reheating signatures on SGWB from ultra-low mass PBH domination
- Enhancement of gravitational waves at Q-ball decay including non-linear density perturbations
- From formation to evaporation: Induced gravitational wave probes of the primordial black hole reheating scenario
- Big Bang Nucleosynthesis Constraint on Baryonic Isocurvature Perturbations
- Universal Gravitational Waves from Interacting and Clustered Solitons
- Induced gravitational waves and baryon asymmetry fluctuations from primordial black hole formation
- Probing Reheating Phase via Non-Helical Magnetogenesis and Secondary Gravitational Waves
- Gravitational Wave Signatures of Primordial Black Hole Reheating in Upcoming Interferometry Missions
- Equation of state during (p)reheating with trilinear interactions
- Gravitational waves from primordial black hole dominance: The effect of inflaton decay rate