Speaker
Description
We explore the generation of primordial black holes (PBHs) and second-order induced gravitational waves (GWs) arising from underdamped isocurvature fluctuations of an axion-like curvaton field. During inflation, the radial component of the curvaton undergoes underdamped evolution, leading to a resonant amplification of the curvaton's quantum fluctuations. This mechanism imprints scale-dependent oscillations and localized bumps in the blue-tilted isocurvature power spectrum. In large regions of parameter space, these enhancements can exceed three orders of magnitude. While standard quadratic curvaton models fail to produce dark matter-like PBHs from Gaussian fluctuations, we show that the dynamically induced non-adiabatic features in our scenario can successfully overcome this limitation. As a result, both PBHs and a detectable stochastic GW background are generated, with distinctive oscillatory signatures in the GW spectrum offering a new observational avenue.
