MEGATRON: how the first stars create an iron metallicity plateau in the smallest dwarf galaxies
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| Main Authors: | , , , , , , , , , , , , , , , , , , , , , , , , , |
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| Format: | Preprint |
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2025
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| _version_ | 1866911195158544384 |
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| author | Rey, Martin P. Katz, Harley Cadiou, Corentin Sanati, Mahsa Agertz, Oscar Blaizot, Jeremy Cameron, Alex J. Choustikov, Nicholas Devriendt, Julien Hauk, Uliana Ji, Alexander P. Jones, Gareth C. Kimm, Taysun Laseter, Isaac Martin-Alvarez, Sergio Matsumoto, Kosei Pearce, Autumn Revaz, Yves Montero, Francisco Rodriguez Rosdahl, Joki Saxena, Aayush Slyz, Adrianne Stiskalek, Richard Storck, Anatole Veenema, Oscar Yee, Wonjae |
| author_facet | Rey, Martin P. Katz, Harley Cadiou, Corentin Sanati, Mahsa Agertz, Oscar Blaizot, Jeremy Cameron, Alex J. Choustikov, Nicholas Devriendt, Julien Hauk, Uliana Ji, Alexander P. Jones, Gareth C. Kimm, Taysun Laseter, Isaac Martin-Alvarez, Sergio Matsumoto, Kosei Pearce, Autumn Revaz, Yves Montero, Francisco Rodriguez Rosdahl, Joki Saxena, Aayush Slyz, Adrianne Stiskalek, Richard Storck, Anatole Veenema, Oscar Yee, Wonjae |
| contents | 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 $z\approx8$ 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 ($\langle [\rm{Fe}/\rm{H}] \rangle \approx -2.5$) at low stellar masses ($M_{\star} \leq 10^5 \, \rm{M}_{\odot}$). 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 ($\approx 10^7\, \rm{M}_{\odot}$) to retain their ejecta. We also predict a tail of $\approx 20\%$ of iron-deficient ($\langle [\rm{Fe}/\rm{H}] \rangle \leq - 3$) 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 $z=0$. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2510_05232 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | MEGATRON: how the first stars create an iron metallicity plateau in the smallest dwarf galaxies Rey, Martin P. Katz, Harley Cadiou, Corentin Sanati, Mahsa Agertz, Oscar Blaizot, Jeremy Cameron, Alex J. Choustikov, Nicholas Devriendt, Julien Hauk, Uliana Ji, Alexander P. Jones, Gareth C. Kimm, Taysun Laseter, Isaac Martin-Alvarez, Sergio Matsumoto, Kosei Pearce, Autumn Revaz, Yves Montero, Francisco Rodriguez Rosdahl, Joki Saxena, Aayush Slyz, Adrianne Stiskalek, Richard Storck, Anatole Veenema, Oscar Yee, Wonjae Astrophysics of Galaxies Cosmology and Nongalactic Astrophysics 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 $z\approx8$ 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 ($\langle [\rm{Fe}/\rm{H}] \rangle \approx -2.5$) at low stellar masses ($M_{\star} \leq 10^5 \, \rm{M}_{\odot}$). 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 ($\approx 10^7\, \rm{M}_{\odot}$) to retain their ejecta. We also predict a tail of $\approx 20\%$ of iron-deficient ($\langle [\rm{Fe}/\rm{H}] \rangle \leq - 3$) 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 $z=0$. |
| title | MEGATRON: how the first stars create an iron metallicity plateau in the smallest dwarf galaxies |
| topic | Astrophysics of Galaxies Cosmology and Nongalactic Astrophysics |
| url | https://arxiv.org/abs/2510.05232 |