Simulating the Cosmic Dawn with Enzo

TL;DR

This paper reviews two decades of using the Enzo hydrodynamic code to simulate the Cosmic Dawn, covering star formation, galaxy assembly, and reionization, and discusses future directions with advanced computational techniques.

Contribution

It provides a comprehensive overview of Enzo-based simulations of the Cosmic Dawn and highlights future challenges requiring more complex models and exascale computing.

Findings

Insights into Population III star formation and transition to Population II

Understanding of early galaxy assembly and high-redshift galaxy statistics

Discussion of future simulation challenges and technological advancements

Abstract

We review two decades of progress using the Enzo hydrodynamic cosmology code to simulate the Cosmic Dawn, a period of roughly 1 billion years beginning with the formation of the first stars in the universe, and ending with cosmic reionization. Using simulations of increasing size and complexity, working up in length and mass scale and to lower redshifts, a connected narrative is built up covering the entire epoch. In the first part of the paper, we draw on results we and our collaborators have achieved using the Enzo cosmological adaptive mesh refinement code. Topics include the formation of Population III stars, the transition to Population II star formation, chemical enrichment, the assembly of the first galaxies, their high redshift galaxy statistics, and their role in reionization. In the second part of the paper we highlight physical difficulties that will require new, more physically complex simulations to address, drawing from a broader literature survey. We discuss the healthy interplay between self-consistent numerical simulations and analytic and semi-analytic approaches. Finally, we discuss technical advances in hardware and software that will enable a new class of more realistic simulations to be carried out on exascale supercomputers in the future.