Peter Klimai

Formation of primordial black holes from non-Gaussian perturbations produced in a waterfall transition

We consider the process of primordial black hole (PBH) formation originated from primordial curvature perturbations produced during waterfall transition (with tachyonic instability), at the end of hybrid inflation. It is known that in such inflation models, rather large values of curvature perturbation amplitudes can be reached, which can potentially cause a significant PBH production in the early Universe. The probability distributions of density perturbation amplitudes in this case can be strongly non-Gaussian, which requires a special treatment. We calculated PBH abundances and PBH mass spectra for the model, and analyzed their dependence on model parameters. We obtained the constraints on the parameters of the inflationary potential, using the available limits on

Constraints on amplitudes of curvature perturbations from primordial black holes

\beta_{PBH}

Axion inflation with gauge field production and primordial black holes

.

Constraints on the induced gravitational wave background from primordial black holes

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

Curvature perturbation spectra from waterfall transition, black hole constraints and non-Gaussianity

{\mathcal{P}}_{\mathcal{R}}(k)

Induced gravitational wave background and primordial black holes

with large (

Cosmological constraints on the curvaton web parameters

\ensuremath{\sim}{10}^{\ensuremath{-}2}\char21{}{10}^{\ensuremath{-}1}

Bound on induced gravitational wave background from primordial black holes

) values at some scale of comoving wave numbers

Constraints on the Number Density of Evaporating Primordial Black Holes for the Chromospheric Evaporation Models

k

Density perturbations in braneworld cosmology and primordial black holes

. 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.