MEGATRON: Reproducing the Diversity of High-Redshift Galaxy Spectra with Cosmological Radiation Hydrodynamics Simulations

@article{katz2026megatron,
  title = {{MEGATRON: Reproducing the Diversity of High-Redshift Galaxy Spectra with Cosmological Radiation Hydrodynamics Simulations}},
  author = {Harley Katz and Martin P. Rey and Corentin Cadiou and Oscar Agertz and Jérémy Blaizot and Alex J. Cameron and Nicholas Choustikov and Julien Devriendt and Uliana Hauk and Gareth C. Jones and Taysun Kimm and Isaac Laseter and Sergio Martin-Alvarez and Kosei Matsumoto and Autumn Pearce and Francisco Rodríguez Montero and Joakim Rosdahl and Mahsa Sanati and Aayush Saxena and Adrianne D. Slyz and Richard Stiskalek and Anatole Storck and Oscar Veenema and Wonjae Yee},
  journal = {The Open Journal of Astrophysics},
  year = {2026},
  month = sep,
  doi = {10.33232/001c.169643},
  url = {https://astro.theoj.org/article/169643-megatron-reproducing-the-diversity-of-high-redshift-galaxy-spectra-with-cosmological-radiation-hydrodynamics-simulations},
  note = {CC BY 4.0},
}

TY  - JOUR
TI  - MEGATRON: Reproducing the Diversity of High-Redshift Galaxy Spectra with Cosmological Radiation Hydrodynamics Simulations
AU  - Harley Katz
AU  - Martin P. Rey
AU  - Corentin Cadiou
AU  - Oscar Agertz
AU  - Jérémy Blaizot
AU  - Alex J. Cameron
AU  - Nicholas Choustikov
AU  - Julien Devriendt
AU  - Uliana Hauk
AU  - Gareth C. Jones
AU  - Taysun Kimm
AU  - Isaac Laseter
AU  - Sergio Martin-Alvarez
AU  - Kosei Matsumoto
AU  - Autumn Pearce
AU  - Francisco Rodríguez Montero
AU  - Joakim Rosdahl
AU  - Mahsa Sanati
AU  - Aayush Saxena
AU  - Adrianne D. Slyz
AU  - Richard Stiskalek
AU  - Anatole Storck
AU  - Oscar Veenema
AU  - Wonjae Yee
PY  - 2026
DA  - 2026/09/30
JO  - The Open Journal of Astrophysics
DO  - 10.33232/001c.169643
UR  - https://astro.theoj.org/article/169643-megatron-reproducing-the-diversity-of-high-redshift-galaxy-spectra-with-cosmological-radiation-hydrodynamics-simulations
AB  - We present the MEGATRON suite of cosmological radiation hydrodynamics simulations following the formation of Milky Way-mass galaxies from the earliest cosmic epochs when Population III stars form to Cosmic Noon. The suite represents the first set of cosmological simulations that couples a vast non-equilibrium thermochemistry network of primordial species, metals, and molecules to multifrequency, on-the-fly radiation transport, allowing us to directly predict the spectral properties of early galaxies. By initializing the simulations at zero metallicity, resolving haloes well below the atomic cooling threshold, reaching parsec-scale resolution, and modeling a Milky Way-mass environment, we aim to address four key science themes: 1) Star formation at cosmic dawn, 2) Galaxy formation and the interstellar medium in the epoch of reionization, 3) The circumgalactic medium towards cosmic noon, and 4) Reionization in a local volume environment and near-field cosmology. In this introductory work, we present an overview of the physical characteristics of high-redshift MEGATRON galaxies and their environment at z > 8 . We present a library of > 175 , 000 simulated galaxy spectra and demonstrate how much of the diversity of galaxy spectra seen by JWST is naturally reproduced in the context of a Λ CDM cosmology. Caveats are discussed, such as the lack of AGN in our simulations and the limitations of our adopted stellar population and chemical yield models. This project represents a step towards making more direct comparisons between simulations and observations and \textcolor{magenta}{is particularly applicable for optimizing methods to infer galaxy properties from existing high-redshift JWST spectra and imaging data.
SN  - 2565-6120
ER  -