Axion cosmology and the energy scale of inflation

By M. Hertzberg, Max Tegmark, Frank Wilczek. 2008

248 citations recorded by the source corpus.

We survey observational constraints on the parameter space of inflation and axions and map out two allowed windows: the classic window and the inflationary anthropic window. The cosmology of the latter is particularly interesting; inflationary axion cosmology predicts the existence of isocurvature fluctuations in the cosmic microwave background, with an amplitude that grows with both the energy scale of inflation and the fraction of dark matter in axions. Statistical arguments favor a substantial value for the latter, and so current bounds on isocurvature fluctuations imply tight constraints on inflation. For example, an axion Peccei-Quinn scale of 10{sup 16} GeV excludes any inflation model with energy scale >3.8x10{sup 14} GeV (r>2x10{sup -9}) at 95% confidence, and so implies negligible gravitational waves from inflation, but suggests appreciable isocurvature fluctuations.

Subfields: Astronomy and Astrophysics, Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/bf2c2dfcad410971f3fb6411c265272bcf9a2e06

How researchers see this paper

The researchers whose trusted networks rank it highest, strongest advocate first. Every researcher gets a different order.

In Astronomy and Astrophysics

In Nuclear and High Energy Physics

Citations in the corpus

Cosmology and Fundamental Physics with the Euclid Satellite (2012, background): “In the mass range m ∼ 10−32 eV ALPs/FCDM have affects on structure not dissimilar from massive neutrinos [49, 837], however there is no degeneracy when the CMB is used in conjunction with large scale structure, due to the different effects on the expansion rate during the radiation era.”
Using the Full Power of the Cosmic Microwave Background to Probe Axion Dark Matter (2017, background): “The axion field then carries deSitter-space vacuum fluctuations with dimensionless power spectrum (e.g. Axenides et al. 1983; Seckel & Turner 1985; Turner & Wilczek 1991; Lyth 1992; Fox et al. 2004; Hertzberg et al. 2008; Komatsu et al. 2009) ∆δφ = Aφ ( k k0 )niso−1 .”
CMB-S4 Science Case, Reference Design, and Project Plan (2019, background): “If HI/2π < fa, then this symmetry is broken during inflation, and the axion acquires uncorrelated isocurvature perturbations [333, 334, 335].”
Dark light, dark matter, and the misalignment mechanism (2011, background): “Such perturbations are highly constrained, and will place an m dependent upper bound on the inflation scale [11,13,18,20–24] for this scenario.”
Freeze-In dark matter with displaced signatures at colliders (2015, background): “This limit applies to the region of parameter space with a post-inflationary scenario [36, 37] where the PQ phase transition occurs after inflation.”
The landscape of QCD axion models (2020, background): “5, tensor modes for single-field inflation are defined in terms of the tensor-to-scalar ratio r which, if measured in the future at the level of r ∼ 10−3, would shut off the pre-inflationary scenario completely [188, 315, 728–731], see also Fig.”
Axion cosmology revisited (2009, methodology): “We will follow refs [13, 15, 42, 45, 80] to put constraints on the PQ scale fa and on the inflationary scale HI .”