2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/168592In theories of axion dark matter with large axion decay constant, temperature variations in the CMB are extremely sensitive to perturbations in the initial axion field, allowing one to place a lower bound on the total amount of inflation. The most stringent bound comes from axion strings, which for axion decay constant f=10^17 GeV would currently be observable at a distance of 6 x 10^16 light-years, nearly ten million times as far away as our horizon.AstrophysicsHigh Energy Physics - PhenomenologyNuclear Theorytext