Flat spectra of cosmic gravitons in the nHz and audio bands

Abstract

The spectra of the relic gravitons are customarily normalized in the low-frequency domain where the signal of the concordance paradigm is expected to peak and this is why their contribution to the temperature and polarization anisotropies of the microwave background is only described by the tensor to scalar ratio. If the consistency relations are broken, the same strategy is accomplished by introducing the tensor spectral index as a further independent parameter. When the dominant component of the spectral energy density is distributed for frequencies much larger than the aHz, the logic behind this conventional approach is much less compelling. The improved bounds in the audio band and the current data from the pulsar timing arrays in the nHz region motivate a new strategy for the absolute normalization of the cosmic background of relic gravitons. After introducing a general four-dimensional action for the analysis of the relic gravitons the new approach is illustrated in the case of conventional and unconventional inflationary models.

arXiv comment33 pages; 5 figures; a paragraph has been added and few typos have been corrected

References in corpus (48)

• Planck 2018 results. X. Constraints on inflation
• BICEP / Keck XIII: Improved Constraints on Primordial Gravitational Waves using Planck, WMAP, and BICEP/Keck Observations through the 2018 Observing Season
• The NANOGrav 12.5-year Data Set: Search For An Isotropic Stochastic Gravitational-Wave Background
• Chern-Simons Modification of General Relativity
• Detecting a stochastic background of gravitational radiation: Signal processing strategies and sensitivities
• Effective Field Theory for Inflation
• Upper Limits on the Isotropic Gravitational-Wave Background from Advanced LIGO's and Advanced Virgo's Third Observing Run
• Singularity-free cosmological solutions of the superstring effective action
• New BBN limits on Physics Beyond the Standard Model from He4
• Limits on the Stochastic Gravitational Wave Background from the North American Nanohertz Observatory for Gravitational Waves
• Upper bounds on the low-frequency stochastic gravitational wave background from pulsar timing observations: current limits and future prospects
• The International Pulsar Timing Array second data release: Search for an isotropic Gravitational Wave Background
• Lorentz-Violating Vector Fields Slow the Universe Down
• On the evidence for a common-spectrum process in the search for the nanohertz gravitational-wave background with the Parkes Pulsar Timing Array
• Search for the isotropic stochastic background using data from Advanced LIGO's second observing run
• Upper Limits on the Stochastic Gravitational-Wave Background from Advanced LIGO's First Observing Run
• Improved Calculation of the Primordial Gravitational Wave Spectrum in the Standard Model
• Damping of Tensor Modes in Cosmology
• Common-red-signal analysis with 24-yr high-precision timing of the European Pulsar Timing Array: Inferences in the stochastic gravitational-wave background search
• Primordial gravitational waves, precisely: The role of thermodynamics in the Standard Model
• Power spectra from an inflaton coupled to the Gauss-Bonnet term
• Analysis of First LIGO Science Data for Stochastic Gravitational Waves
• Improved Upper Limits on the Stochastic Gravitational-Wave Background from 2009-2010 LIGO and Virgo Data
• Upper Limits on a Stochastic Background of Gravitational Waves
• Relic gravitational waves and their detection
• Comment on "Damping of Tensor Modes in Cosmology"
• Constraints of relic gravitational waves by Pulsar Timing Array: Forecasts for the FAST and SKA projects
• Some Inflationary Einstein-Aether Cosmologies
• Analytic spectrum of relic gravitational waves modified by neutrino free streaming and dark energy
• Upper limits on a stochastic gravitational-wave background using LIGO and Virgo interferometers at 600-1000 Hz
• Searching for stochastic gravitational waves using data from the two co-located LIGO Hanford detectors
• Stochastic backgrounds of relic gravitons, T$\Lambda$CDM paradigm and the stiff ages
• Constant-roll inflation in scalar-tensor gravity
• Big Bang nucleosynthesis, matter-antimatter regions, extra relativistic species, and relic gravitational waves
• An analytic description of the damping of gravitational waves by free streaming neutrinos
• Brane Constant-roll Inflation
• Scalar and Tensor Inhomogeneities from Dimensional Decoupling
• Constant roll inflation in multifield models
• Constraint on the early Universe by relic gravitational waves: From pulsar timing observations
• Sensitivity of wide band detectors to quintessential gravitons
• The refractive index of relic gravitons
• Stability of the aether
• Sensitivity of a VIRGO pair to stochastic GW backgrounds
• Post-inflationary thermal histories and the refractive index of relic gravitons
• Damping of tensor modes in inflation
• Polarized backgrounds of relic gravitons
• The refractive index of the relic gravitons and the nHz band
• Curvature perturbations from dimensional decoupling

Cited by in corpus (1)

• Relic gravitons and pulsar timing arrays: a theoretical viewpoint