FIREbox: Simulating galaxies at high dynamic range in a cosmological volume

TL;DR

FIREbox is a high-resolution cosmological simulation suite that models galaxy evolution, capturing complex interstellar medium physics and providing predictions consistent with many observations, while also revealing limitations of stellar feedback models.

Contribution

This work introduces FIREbox, a novel high-resolution cosmological simulation that accurately models galaxy properties and the interstellar medium in a fully cosmological context.

Findings

Simulated galaxy properties broadly match observational data.

Reproduces evolution of cosmic HI density and column density distribution.

Identifies limitations of stellar feedback in modeling massive galaxy formation.

Abstract

We introduce a suite of cosmological volume simulations to study the evolution of galaxies as part of the Feedback in Realistic Environments project. FIREbox, the principal simulation of the present suite, provides a representative sample of galaxies (~1000 galaxies with Mstar > 10^8 Msun at z=0) at a resolution (~20 pc, m_b ~ 6x10^4 Msun) comparable to state-of-the-art galaxy zoom-in simulations. FIREbox captures the multiphase nature of the interstellar medium in a fully cosmological setting (L=22.1 Mpc) thanks to its exceptionally high dynamic range (~10^6) and the inclusion of multi-channel stellar feedback. Here, we focus on validating the simulation predictions by comparing to observational data. We find that simulated galaxies with Mstar < 10^{10.5-11} Msun have star formation rates, gas masses, and metallicities in broad agreement with observations. These galaxy scaling relations extend to low masses (Mstar ~ 10^7 Msun) and follow a (broken) power-law relationship. Also reproduced are the evolution of the cosmic HI density and the HI column density distribution at z~0-5. At low z, FIREbox predicts a peak in the stellar-mass--halo-mass relation, but also a higher abundance of massive galaxies and a higher cosmic star formation rate density than observed, showing that stellar feedback alone is insufficient to reproduce the properties of massive galaxies at late times. Given its high resolution and sample size, FIREbox offers a baseline prediction of galaxy formation theory in a $\Lambda$CDM Universe while also highlighting modeling challenges to be addressed in next-generation galaxy simulations.