# Post-inflationary structure formation boosted by parametric self-resonance

**Authors:** Benedikt Eggemeier, Peter Hayman, Jens C. Niemeyer, Richard Easther  
**arXiv:** [2311.08780](https://arxiv.org/abs/2311.08780)  
**Date:** 2023-11-15  
**Summary page:** https://www.summarizepaper.com/en/arxiv-id/2311.08780v2/

## Key points

- Study focuses on post-inflationary Universe dynamics during matter-dominated expansion
- Research involves simulations of resonant phase and gravitational collapse of inflaton field
- Transition from Klein-Gordon to Schrödinger-Poisson description for accurate non-relativistic gravitational dynamics
- Resonance leads to overdensities resulting in prompt gravitational collapse after resonance ends
- Formation of solitonic cores inside inflaton halos with complex gravitational dynamics on small scales (10^-27 m)
- Findings contribute to understanding nonlinear post-inflationary gravitational processes and cosmic evolution

## Summary

The study "Post-inflationary structure formation boosted by parametric self-resonance" by Benedikt Eggemeier, Peter Hayman, Jens C. Niemeyer, and Richard Easther delves into the dynamics of the post-inflationary Universe during a period of effective matter-dominated expansion. This epoch presents a unique opportunity for amplifying initial fluctuations and gravitational collapse of inflaton perturbations. The researchers conduct groundbreaking high-resolution simulations covering the resonant phase and subsequent gravitational collapse of the inflaton field. By transitioning from a full Klein-Gordon treatment to a computationally efficient Schr\"odinger-Poisson description, they accurately capture the non-relativistic gravitational dynamics. Focusing on a specific scenario where resonance leads to overdensities on the order of $10^{-1}$, they observe prompt gravitational collapse after resonance ends. Notably, solitonic cores form inside inflaton halos, showcasing complex gravitational dynamics on scales as small as $10^{-27}\,\mathrm{m}$. These findings significantly expand our understanding of nonlinear post-inflationary gravitational processes and shed light on previously unexplored aspects of cosmic evolution.