Axion global fits with Peccei-Quinn symmetry breaking before inflation using GAMBIT

Understand

We present global fits of cosmologically stable axion-like particle and QCD axion models in the mass range 0.1 neV to 10 eV.

• We focus on the case where the Peccei-Quinn symmetry is broken before the end of inflation, such that the initial value of the axion field can be considered to be homogeneous throughout the visible Universe.
• We include detailed likelihood functions from light-shining-through-wall experiments, haloscopes, helioscopes, the axion relic density, horizontal branch stars, supernova 1987A, white dwarf cooling, and gamma-ray observations.
• We carry out both frequentist and Bayesian analyses, with and without the inclusion of white dwarf cooling.