2026-09-30 バース大学
Simulation of the first galaxies in the Universe. Credit: Harley B. Katz, Martin P. Rey
＜関連情報＞
- https://www.bath.ac.uk/announcements/new-simulations-connect-the-first-stars-to-cosmic-fingerprints-still-visible-today/
- https://astro.theoj.org/article/169605-megatron-how-the-first-stars-can-create-an-iron-metallicity-plateau-in-the-smallest-dwarf-galaxies
- https://arxiv.org/abs/2510.05232v2
メガトロン：最初の星々が最小の矮小銀河に鉄の金属量プラトーを作り出す方法 MEGATRON: how the first stars can create an iron metallicity plateau in the smallest dwarf galaxies
Martin Rey,Harley Katz,Corentin Cadiou,Mahsa Sanati,Oscar Agertz,Jeremy Blaizot,Alex J. Cameron,Nicholas Choustikov,Julien Devriendt,Uliana Hauk,Alexander P. Ji,Gareth C. Jones,Taysun Kimm,Isaac Laseter,Sergio Martin-Alvarez,Kosei Matsumoto,Autumn Pearce,Yves Revaz,Francisco Rodriguez Montero,Joki Rosdahl,Aayush Saxena,Adrianne Slyz,Richard Stiskalek,Anatole Storck,Oscar Veenema,Wonjae Yee
The Open Journal of Astrophysics Published:September 30, 2026
DOI:https://doi.org/10.33232/001c.169605
Abstract
We study the stellar mass-iron metallicity relation of dwarf galaxies in the new high-resolution MEGATRON cosmological radiation-hydrodynamics simulations. These simulations model galaxy formation up to z≈8 in a region that will collapse into a Milky-Way-like galaxy at z=0, while self-consistently tracking Population III and II (Pop.~III, Pop.~II) star formation, feedback and chemical enrichment. MEGATRON dwarf galaxies are in excellent agreement with the observed stellar mass-metallicity relation at z=0, including an over-abundance of dwarfs along a flat plateau in metallicity (⟨[Fe/H]⟩≈−2.5) at low stellar masses (M⋆≤105M⊙). We tie this feature to the chemical enrichment of dwarf galaxies by Pop.~III pair-instability supernova (PISN) explosions. The strong Lyman-Werner background (LW) from the protogalaxy ensures that PISNe occur in haloes massive enough (≈107M⊙) to retain their ejecta. We also predict a tail of ≈20% of iron-deficient (⟨[Fe/H]⟩≤−3) dwarf galaxies. We show that both plateau and tail (i) are robust to large variations in Pop.~II feedback assumptions, and (ii) survive in bound satellites surrounding the central galaxy at z=0.
