How warm are non-thermal relics? Lyman-$\alpha$ bounds on out-of-equilibrium dark matter

Understand

We investigate the power spectrum of Non-Cold Dark Matter (NCDM) produced in a state out of thermal equilibrium.

• We consider dark matter production from the decay of scalar condensates (inflaton, moduli), the decay of thermalized and non-thermalized particles, and from thermal and non-thermal freeze-in.
• For each case, we compute the NCDM phase space distribution and the linear matter power spectrum, which features a cutoff analogous to that for Warm Dark Matter (WDM).
• This scale is solely determined by the equation of state of NCDM.