Freeze-in dark matter perturbations are adiabatic

We show that the large-scale perturbations in the dark matter generated by the freeze-in mechanism are only of adiabatic nature. The freeze-in mechanism is not at odds with the current stringent constraints on isocurvature perturbations.

Automated summary

The large-scale perturbations in dark matter generated by the freeze-in mechanism are shown to be only of adiabatic nature, which is not contradictory to the current stringent constraints on isocurvature perturbations.