Starting Cosmological Simulations from the Big Bang.

Area of Science:

• Cosmology
• Astrophysics
• Computational Physics

Background:

• Cosmic large-scale structure (LSS) is crucial for testing fundamental physics against astronomical observations.
• Current modeling methods, N-body simulations and perturbative techniques, have limitations.
• A unified approach is needed to overcome these shortcomings.

Purpose of the Study:

• To present the first unified numerical approach for modeling cosmic large-scale structure.
• To demonstrate the convergence and capabilities of this new simulation method.
• To enable fast, self-consistent, and UV-complete forward modeling of LSS observables.

Main Methods:

• Developed novel time integration and discreteness reduction schemes.
• Implemented a unified numerical approach for N-body simulations.
• Demonstrated field-level convergence of the simulations.

Main Results:

• Simulations can be initialized directly at time zero.
• The method achieves agreement with high-order Lagrangian perturbation theory in the fluid limit.
• The approach enables fast and self-consistent forward modeling.

Conclusions:

• The new unified numerical approach overcomes limitations of existing methods.
• This technique provides a powerful tool for studying cosmic large-scale structure.
• It facilitates connecting fundamental physics with astronomical observations through improved LSS modeling.