Abstract.
I will discuss a novel mechanism for the production of dark matter (DM) from a thermal bath, based on the idea that DM particles $\chi$ can transform heat bath particles $\psi$: $\chi \psi \to \chi \chi$. For a small initial abundance of $\chi$ this leads to an exponential growth of the DM number density. We demonstrate that this mechanism complements freeze-in and freeze-out production in a generic way, opening new parameter space to explain the observed DM abundance. An interesting specific scenario is the case of sterile neutrinos with secret interactions, where the exponential growth opens up significant new parameter space where sterile neutrinos make up all of the observed dark matter consistent with bounds from X-rays, structure formation and DM self-interactions.
(The slides will be available here)