Amplification of Primordial Gravitational Waves by a Geometrically Driven non-canonical Reheating Era

Abstract

In order to describe inflation in general relativity, scalar fields must inevitably be used, with all the setbacks of that description. On the other hand, $f(R)$ gravity and other modified gravity theories seem to provide a unified description of early and late-time dynamics without resorting to scalar or phantom theories. The question is, can modified gravity affect directly the mysterious radiation domination era? Addressing this question is the focus in this work, and we shall consider the case for which in the early stages of the radiation domination era, namely during the reheating era, the background equation of state parameter is different from $w=1/3$. As we show, in the context of $f(R)$ gravity, an abnormal reheating era can affect the primordial gravitational wave energy spectrum today. Since future interferometers will exactly probe this era, which consists of subhorizon modes that reentered the horizon during the early stages of the radiation domination era, the focus in this work is how a short abnormal reheating era that deviates from the standard perfect fluid pattern with $w\ne 1/3$, and generated by higher order curvature terms, can affect the primordial gravitational wave energy spectrum. Using a WKB approach, we calculate the effect of an $f(R)$ gravity generated abnormal reheating era, and as we show the primordial gravitational wave spectrum is significantly amplified, a result which is in contrast to the general relativistic case, where the effect is minor.

arXiv commentFortschritte der Physik Accepted

References in corpus (56)

• Unified cosmic history in modified gravity: from F(R) theory to Lorentz non-invariant models
• Extended Theories of Gravity
• Modified Gravity Theories on a Nutshell: Inflation, Bounce and Late-time Evolution
• Modified gravity with negative and positive powers of the curvature: unification of the inflation and of the cosmic acceleration
• Particle Physics Models of Inflation and the Cosmological Density Perturbation
• GW190814: Gravitational Waves from the Coalescence of a 23 M${}_{\odot }$ Black Hole with a 2.6 M${}_{\odot }$ Compact Object
• Sensitivity Studies for Third-Generation Gravitational Wave Observatories
• Possibility of Direct Measurement of the Acceleration of the Universe Using 0.1 Hz Band Laser Interferometer Gravitational Wave Antenna in Space
• Cosmological Backgrounds of Gravitational Waves
• Gravitational Radiation from First-Order Phase Transitions
• Physics, Astrophysics and Cosmology with Gravitational Waves
• Palatini Approach to Modified Gravity: f(R) Theories and Beyond
• Beyond LISA: Exploring Future Gravitational Wave Missions
• Unifying inflation with LambdaCDM epoch in modified f(R) gravity consistent with Solar System tests
• The Large Scale Structure of f(R) Gravity
• Reconciling dark energy models with f(R) theories
• Inflationary Cosmology
• One-loop f(R) gravity in de Sitter universe
• Constraining f(R) Gravity as a Scalar Tensor Theory
• Fundamental Physics with the Square Kilometre Array
• The Quest for B Modes from Inflationary Gravitational Waves
• Cosmological reconstruction of realistic modified F(R) gravities
• Black holes, cosmological solutions, future singularities, and their thermodynamical properties in modified gravity theories
• Limit to General Relativity in f(R) theories of gravity
• Probing the early universe with inflationary gravitational waves
• Improved Calculation of the Primordial Gravitational Wave Spectrum in the Standard Model
• Tensor Perturbations in Inflationary Models as a Probe of Cosmology
• Implications of the NANOGrav results for inflation
• Stability of Cosmological Solution in f(R) Models of Gravity
• Direct detection of the inflationary gravitational wave background
• Generalized framework for testing gravity with gravitational-wave propagation. I. Formulation
• de Sitter space and the equivalence between f(R) and scalar-tensor gravity
• On the LCDM Universe in f(R) gravity
• LISA for Cosmologists: Calculating the Signal-to-Noise Ratio for Stochastic and Deterministic Sources
• The evolution of density perturbations in f(R) gravity
• Junction Conditions in f(R) Theories of Gravity
• Generalized framework for testing gravity with gravitational-wave propagation. II. Constraints on Horndeski theory
• Precision calculations of the gravitational wave background spectrum from inflation
• Sensitivity to a Frequency-Dependent Circular Polarization in an Isotropic Stochastic Gravitational Wave Background
• f(R) gravity theory and CMBR constraints
• Aspects of cosmological expansion in F(R) gravity models
• Prospects for direct detection of primordial gravitational waves
• Cosmic history of viable exponential gravity: Equation of state oscillations and growth index from inflation to dark energy era
• Measuring the spectrum of primordial gravitational waves with CMB, PTA and Laser Interferometers
• Thermal history of the plasma and high-frequency gravitons
• Constraints of relic gravitational waves by Pulsar Timing Array: Forecasts for the FAST and SKA projects
• Constraints on primordial gravitational waves from the Cosmic Microwave Background
• Unification of a Bounce with a Viable Dark Energy Era in Gauss-Bonnet Gravity
• Detecting Relic Gravitational Waves by Pulsar Timing Arrays: Effects of Cosmic Phase Transitions and Relativistic Free-Streaming Gases
• The evolution of gravitons in accelerating cosmologies: the case of extended gravity
• Double-peaked inflation model: Scalar induced gravitational waves and primordial-black-hole suppression from primordial non-Gaussianity
• Propagating Speed of Primordial Gravitational Waves
• Pre-Inflationary Bounce Effects on Primordial Gravitational Waves of $f(R)$ Gravity
• Gravity's Islands: Parametrizing Horndeski Stability
• Primordial gravitational waves in Horndeski gravity
• Improved calculation of relic gravitational waves

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• Inflationary interpretation of the stochastic gravitational wave background signal detected by pulsar timing array experiments
• Inflation, the Hubble Tension and Early Dark Energy: an alternative overview
• Towards a reliable calculation of relic radiation from primordial gravitational waves
• Inflationary Potential as seen from Different Angles: Model Compatibility from Multiple CMB Missions
• Tracking the Multifield Dynamics with Cosmological Data: A Monte Carlo approach
• The Effect of Non-minimally Coupled Scalar Field on Gravitational Waves from First-order Vacuum Phase Transitions
• The scalar-torsion gravity corrections in the first-order inflationary models
• Dark Universe inspired by the Kaluza-Klein gravity and impact on Primordial Gravitational Waves
• Induced electromagnetic radiation from a charged cloud in a plane gravitational wave