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Primordial Black Holes

M. Yu. Khlopov

TL;DR

Primordial black holes offer a unique probe of physics in the early Universe by encoding information from multiple high-energy processes. The paper surveys formation channels—dust-like domination by superheavy particles, inflationary-stage phase-transition spikes, and first-order bubble collisions—along with observational constraints from Hawking evaporation and gravitino production that translate into limits on small-scale power spectra and new physics scenarios. It highlights how PBH relics, closed walls, and PBH clusters could influence dark matter, structure formation, and gravitational-wave backgrounds, thereby linking cosmology to particle theories beyond the Standard Model. Overall, PBHs provide a powerful framework for testing cosmoarcheology and the symmetry-breaking patterns of fundamental physics at ultra-high energies.

Abstract

Primordial black holes (PBHs) are a profound signature of primordial cosmological structures and provide a theoretical tool to study nontrivial physics of the early Universe. The mechanisms of PBH formation are discussed and observational constraints on the PBH spectrum, or effects of PBH evaporation, are shown to restrict a wide range of particle physics models, predicting an enhancement of the ultraviolet part of the spectrum of density perturbations, early dust-like stages, first order phase transitions and stages of superheavy metastable particle dominance in the early Universe. The mechanism of closed wall contraction can lead, in the inflationary Universe, to a new approach to galaxy formation, involving primordial clouds of massive BHs created around the intermediate mass or supermassive BH and playing the role of galactic seeds.

Primordial Black Holes

TL;DR

Primordial black holes offer a unique probe of physics in the early Universe by encoding information from multiple high-energy processes. The paper surveys formation channels—dust-like domination by superheavy particles, inflationary-stage phase-transition spikes, and first-order bubble collisions—along with observational constraints from Hawking evaporation and gravitino production that translate into limits on small-scale power spectra and new physics scenarios. It highlights how PBH relics, closed walls, and PBH clusters could influence dark matter, structure formation, and gravitational-wave backgrounds, thereby linking cosmology to particle theories beyond the Standard Model. Overall, PBHs provide a powerful framework for testing cosmoarcheology and the symmetry-breaking patterns of fundamental physics at ultra-high energies.

Abstract

Primordial black holes (PBHs) are a profound signature of primordial cosmological structures and provide a theoretical tool to study nontrivial physics of the early Universe. The mechanisms of PBH formation are discussed and observational constraints on the PBH spectrum, or effects of PBH evaporation, are shown to restrict a wide range of particle physics models, predicting an enhancement of the ultraviolet part of the spectrum of density perturbations, early dust-like stages, first order phase transitions and stages of superheavy metastable particle dominance in the early Universe. The mechanism of closed wall contraction can lead, in the inflationary Universe, to a new approach to galaxy formation, involving primordial clouds of massive BHs created around the intermediate mass or supermassive BH and playing the role of galactic seeds.

Paper Structure

This paper contains 16 sections, 70 equations, 3 figures.

Table of Contents

  1. Introduction
  2. PBHs as cosmological reflection of new physics
  3. PBHs from early dust-like stages
  4. Dominance of superheavy particles in early Universe
  5. Spikes from phase transitions on inflationary stage
  6. First order phase transitions as a source of black holes in the early Universe
  7. Evolution of field configuration in collisions of vacuum bubbles
  8. Gravitational collapse of FVB and BH creation
  9. First order phase transitions in the early Universe
  10. Gravitino production by PBH evaporation and constraints on the inhomogeneity of the early Universe
  11. Limits on the PBH density
  12. Cosmological consequences
  13. Massive Primordial Black Holes from collapse of closed walls
  14. Structures from succession of U(1) phase transitions
  15. Formation of closed walls in inflationary Universe
  16. ...and 1 more sections

Figures (3)

  • Figure 1: Constraints of KBgrain on the fraction of the Universe going into PBHs (adapted from carr1carrMGLGreenpolnarev). The two curves obtained with gravitinos emission in mSUGRA correspond to $m_{3/2}$ = 100 GeV (lower curve in the high mass range) and $m_{3/2}$ = 1 TeV (upper curve in the high mass range)
  • Figure 2: Constraints of KBgrain on the fraction of the Universe going into PBHs (adapted from carr1carrMGLGreenpolnarev). The curve obtained with gravitinos emission in GMSB correspond to $m_{3/2}=10$ GeV and scales with gravitino mass as $\propto m_{3/2}^{-1}$.
  • Figure 3: Upper limit from KBgrain on the spectral index of the power spectrum as a function of the amplitude of the step.