Neutrino background spectra from primordial black hole evaporations: dependence on the initial mass spectrum

Comparative analysis of different types of initial mass spectra of primordial black holes (PBHs) is carried out. It is assumed that primordial density fluctuations have power law spectrum and the spectral index is constant throughout all scales. It is shown that densities of background radiations (neutrinos, gamma-quanta) from PBH evaporations strongly depend on the type of gravitational collapse and on the way of taking into account the spread of horizon masses at which PBHs can form. Constraints on spectral index values based on PBH evaporation process and on atmospheric and solar neutrino data are obtained.