Axion Monodromy Oscillons

Oscillons are localized, massive, long-lived and oscillating classical scalar field configurations. We assume that dark matter is an axion with a monodromy. We find that oscillons can be formed generically through parametric resonance, and these survive until matter-radiation equality (and possibly beyond) for axions in the ultra light mass range, m \approx 10^{-21} eV. Being overdensities, these oscillons can act as seeds for structure formation. 

This is a work in progress with Oriol Pujolàs and Fabrizio Rompineve (IFAE)