Gravitational Collapse in the Post-Inflationary Universe

Abstract

The Universe may pass through an effectively matter-dominated epoch between inflation and Big Bang Nucleosynthesis during which gravitationally bound structures can form on subhorizon scales. In particular, the inflaton field can collapse into inflaton halos, forming "large scale" structure in the very early universe. We combine N-body simulations with high-resolution zoom-in regions in which the non-relativistic Schrödinger-Poisson equations are used to resolve the detailed, wave-like structure of inflaton halos. Solitonic cores form inside them, matching structure formation simulations with axion-like particles in the late-time universe. We denote these objects \textit{inflaton stars}, by analogy with boson stars. Based on a semi-analytic formalism we compute their overall mass distribution which shows that some regions will reach overdensities of $10^{15}$ if the early matter-dominated epoch lasts for 20 $e$-folds. The radii of the most massive inflaton stars can shrink below the Schwarzschild radius, suggesting that they could form primordial black holes prior to thermalization.

9 pages, 6 figures, accepted by PRD

References in corpus (10)

• Ultralight scalars as cosmological dark matter
• Cosmic Structure as the Quantum Interference of a Coherent Dark Wave
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• Constraining Inflation
• Formation of inflaton halos after inflation

Cited by in corpus (12)

• Structure of Axion Miniclusters
• Polarized Vector Oscillons
• Deep zoom-in simulation of a fuzzy dark matter galactic halo
• Soliton Formation and the Core-Halo Mass Relation: An Eigenstate Perspective
• Axion minivoids and implications for direct detection
• Soliton Merger Rates and Enhanced Axion Dark Matter Decay
• Maximum mass of relativistic self-gravitating Bose-Einstein condensates with repulsive or attractive $|\phi {|}^4$ self-interaction
• Improved Mixed Dark Matter Halo Model for Ultralight Axions
• Threshold of Primordial Black Hole Formation against Velocity Dispersion in Matter-Dominated Era
• Stochastic Gravitational Waves from Post-inflationary Structure Formation
• Production of PBHs from inflaton structure
• A Faster Growth of Perturbations in an Early Matter Dominated Epoch: Primordial Black Holes and Gravitational Waves