Primordial black holes as dark matter: The power spectrum and evaporation of early structures

We consider the possibility that massive primordial black holes are the dominant form of dark matter. Black hole formation adds a Poisson noise to the matter density fluctuations. We use Lyalpha forest observations to constrain this Poisson term, which constrains the black hole masses to be less than approximately a few times 10(4) M-.. We also find that structures with less than similar to 10(3) black holes evaporate by now.