Gravitational effects on oscillon lifetimes

Abstract

Many scalar field theories with attractive self-interactions support exceptionally long-lived, spatially localized and time-periodic field configurations called oscillons (axion stars). A detailed study of their longevity is important for understanding their applications in cosmology. In this paper, we study gravitational effects on the decay rate and lifetime of dense oscillons, where self-interactions are more or at least equally important compared with gravitational interactions. As examples, we consider the α-attractor T-model of inflation and the axion monodromy model, where the potentials become flatter than quadratic at large field values beyond some characteristic field distance F from the minimum. For oscillons with field amplitudes of \U0001d4aa(F) and for F ≪ 0.1 M pl, we find that their evolution is almost identical to cases where gravity is ignored. For F ∼ 0.1 M pl, however, including gravitational interactions reduces the lifetime slightly.