Improved Calculation of the Primordial Gravitational Wave Spectrum in the Standard Model
By Yuki Watanabe, E. Komatsu. 2006
216 citations recorded by the source corpus.
We show that the energy density spectrum of the primordial gravitational waves has characteristic features due to the successive changes in the relativistic degrees of freedom during the radiation era. These changes make the evolution of radiation energy density deviate from the conventional adiabatic evolution, {rho}{sub r}{proportional_to}a{sup -4}, and thus cause the expansion rate of the universe to change suddenly at each transition which, in turn, modifies the spectrum of primordial gravitational waves. We take into account all the particles in the standard model of elementary particles. In addition, free-streaming of neutrinos damps the amplitude of gravitational waves, leaving characteristic features in the energy density spectrum. Our calculations are solely based on the standard model of cosmology and particle physics, and therefore these features must exist. Our calculations significantly improve the previous ones which ignored these effects and predicted a smooth, featureless spectrum.
Subfields: Astronomy and Astrophysics, Nuclear and High Energy Physics
View Paper: https://www.semanticscholar.org/paper/28c97b5b30f3e3aed31f6284a0c8414e1cb58a99
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Citations in the corpus
- FIVE-YEAR WILKINSON MICROWAVE ANISOTROPY PROBE OBSERVATIONS: COSMOLOGICAL INTERPRETATION (2008, unknown): “…as f(φ)RµνρσR̃ µνρσ where f(φ) is an arbitrary function of a scalar field, Rµνρσ is the Riemann tensor, and R̃µνρσ is a dual tensor (Lue et al. 1999), both 21 See, e.g., Watanabe & Komatsu (2006) for the spectrum of the primordial gravitational waves itself. polarization states are statistically…”
- Gravitational waves induced by scalar perturbations with a lognormal peak (2020, background): “The GWs induced by such primordial scalar perturbation is also nearly scale-invariant at frequencies higher than 10−15 Hz, but the amplitude is negligibly small to be detected [14], and perhaps smaller than GWs from the primordial tensor perturbation [41, 42].”
- Primordial gravitational waves, precisely: the role of thermodynamics in the Standard Model (2018, methodology): “[29], we note that lattice QCD simulations yielded Tc ∼ 150 MeV afterwards [103,104].”
- Gravitational-wave cosmology across 29 decades in frequency (2015, background): “Note that, in evaluating the observed GW spectrum, we neglect the effects of neutrino free streaming [38] and phase transitions occurring in the early Universe [35].”
- New physics from the polarized light of the cosmic microwave background (2022, background): “The structures seen in the spectrum reflect various events in the early Universe 171–173 .”