Constraints on amplitudes of curvature perturbations from primordial black holes

TL;DR

This paper investigates how different models of primordial curvature perturbations influence the formation of primordial black holes, deriving constraints from observational data on their mass spectrum and evaporation signatures.

Contribution

It provides a detailed calculation of PBH mass spectra from various curvature perturbation models, incorporating time-dependent gravitational potential effects.

Findings

Constraints on model parameters from cosmic background data.

Predictions of neutrino and photon spectra from PBH evaporation.

Discussion of PBH contribution to the Galactic 511 keV line.

Abstract

We calculate the primordial black hole (PBH) mass spectrum produced from a collapse of the primordial density fluctuations in the early Universe using, as an input, several theoretical models giving the curvature perturbation power spectra with large (~ 0.01 - 0.1) values at some scale of comoving wave numbers k. In the calculation we take into account the explicit dependence of gravitational (Bardeen) potential on time. Using the PBH mass spectra, we further calculate the neutrino and photon energy spectra in extragalactic space from evaporation of light PBHs, and the energy density fraction contained in PBHs today (for heavier PBHs). We obtain the constraints on the model parameters using available experimental data (including data on neutrino and photon cosmic backgrounds). We briefly discuss the possibility that the observed 511 keV line from the Galactic center is produced by annihilation of positrons evaporated by PBHs.