Cosmological Structure Formation in Decaying Dark Matter Models

Understand

The standard cold dark matter (CDM) model predicts too many and too dense small structures.

• We consider an alternative model that the dark matter undergoes two-body decays with cosmological lifetime $\tau$ into only one type of massive daughters with non-relativistic recoil velocity $V_k$.
• This decaying dark matter model (DDM) can suppress the structure formation below its free-streaming scale at time scale comparable to $\tau$.
• Comparing with warm dark matter (WDM), DDM can better reduce the small structures while being consistent with high redshfit observations.