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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 $$M_{\rm star}\gt 10^8\, M_\odot$$ at z = 0) at a resolution ($$\Delta {}x\sim {}20\, {\rm pc}$$ , $$m_{\rm b}\sim {}6\times {}10^4\, M_\odot$$ ) 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 (≳106) and the inclusion of multichannel stellar feedback. Here, we focus on validating the simulation predictions by comparing to observational data. We find that star formation rates, gas masses, and metallicities of simulated galaxies with $$M_{\rm star}\lt 10^{10.5-11}\, M_\odot$$ broadly agree with observations. These galaxy scaling relations extend to low masses ($$M_{\rm star}\sim {}10^7\, M_\odot$$ ) 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 ΛCDM Universe while also highlighting modelling challenges to be addressed in next-generation galaxy simulations.
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This content will become publicly available on November 24, 2026
Discs no more: the morphology of low-mass simulated galaxies in FIREbox
ABSTRACT We study the morphology of hundreds of simulated central galaxies in the stellar mass range $$M_\star =$$ 107.5–1011 $$\rm M_\odot$$ from the FIREbox cosmological volume. We demonstrate that FIREbox is able to predict a wide variety of morphologies, spanning from disc-dominated objects to spheroidal galaxies supported by stellar velocity dispersion. However, the simulations predict a strong relation between morphology (degree of rotational support) and stellar mass: galaxies comparable to the Milky Way are often disc-dominated while the presence of stellar discs mostly vanishes for dwarfs with $$M_\star < 10^9 ~$$\rm M_\odot$$. This defines a ‘morphology transition’ regime for galaxies with $$10^9 < M_\star /\rm {M_\odot }< 10^{10}$$ in which discs become increasingly common, but below which discs are rare. We show that burstiness in the star formation history and the deepening of the gravitational potential strongly correlate in our simulations with this transition regime, with discs forming in objects with lower levels of burstiness in the last $$\sim 6$$ Gyr and haloes with mass $$\sim 10^{11} ~ \rm {{\rm M}_{\odot }}$$ and above. While observations support a transition towards thicker discs in the regime of dwarfs, our results are in partial disagreement with observations of at least some largely rotationally supported gas discs in dwarfs with $$M_\star < 10^9$$\rm M_\odot$$. This study highlights dwarf morphology as a fundamental benchmark for testing future galaxy formation models.
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- PAR ID:
- 10655048
- Publisher / Repository:
- MNRAS
- Date Published:
- Journal Name:
- Monthly Notices of the Royal Astronomical Society
- Volume:
- 544
- Issue:
- 4
- ISSN:
- 0035-8711
- Page Range / eLocation ID:
- 4651 to 4664
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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