The Open Journal of Astrophysics· 2026Q1
MEGATRON: how the first stars can create an iron metallicity plateau in the smallest dwarf galaxies
- 1citations
- Q1SCImago
- 2026year
Short summary
The MEGATRON simulations reveal that the first stars (Population III) exploding as pair-instability supernovae (PISNe) create a flat iron metallicity plateau at low stellar masses in dwarf galaxies, matching observations.
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Key points
- MEGATRON simulations match observed dwarf galaxy stellar mass-iron metallicity relation, including a low-mass plateau.
- Population III pair-instability supernovae (PISNe) are identified as the source of the iron metallicity plateau.
- A strong Lyman-Werner background is crucial for PISNe to occur in halos massive enough to retain ejecta.
- Simulations predict a tail of ~20% iron-deficient dwarf galaxies.
AI-generated from the title and abstract; the full text is not read.
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 () at low stellar masses (). 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 () to retain their ejecta. We also predict a tail of ≈ 20 % of iron-deficient () 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 .
The authors' abstract, as published at the source. The Open Journal of Astrophysics, 2026 · DOI ↗
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Field: Instrumentation
InstrumentationPhysics and Astronomy