Reheating after Axion Inflation

In modern cosmology, it is generally assumed that after inflation, the energy stored in the inflaton field is transferred to radiation through a process known as reheating. Axion-like particles have attracted  attention as inflaton candidates, since their shift symmetry can naturally protect the flatness of the inflaton potential. In this talk, I will discuss the reheating process in a model where an axion-like inflaton is coupled to non-Abelian gauge fields through a Chern-Simons coupling. In this scenario, the inflaton energy can be transferred efficiently through resonant gauge-field production, as is familiar from preheating analyses, and through thermal dissipation. One might therefore expect reheating to complete efficiently. However, an important question remains. Even a small remnant of the inflaton  can eventually dominate the energy density of the Universe again. I will explain how reheating is completed in this context, and discuss the conditions under which the Universe successfully becomes radiation dominated. This talk is based on arXiv:2503.01228, JCAP 07 (2025), 002.