Signatures of Very Massive Stars in the Epoch of Reionization
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arXiv
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| Autori principali: | , , , , |
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| Natura: | Preprint |
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2026
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| author | Marques-Chaves, Rui Martins, Fabrice Schaerer, Daniel Dessauges-Zavadsky, Miroslava Palacios, Ana |
| author_facet | Marques-Chaves, Rui Martins, Fabrice Schaerer, Daniel Dessauges-Zavadsky, Miroslava Palacios, Ana |
| contents | We present ultra-deep ($\simeq 20-30$ hours), rest-frame UV spectroscopy with NIRSpec/JWST of two UV-bright galaxies at $z\sim 8.7$, CEERS-1019 and CEERS-1025 ($Z_{\rm neb} \simeq 0.1 Z_{\odot}$). The spectra reveal exceptionally strong P-Cygni profiles in wind lines (NV $λ$1240 and CIV $λ$1550) and significant broad and strong HeII $λ$1640 emission ($\rm EW\simeq 2-4$ A). We compare the observations with synthetic stellar population models at $Z_{\star} \simeq 0.1 Z_{\odot}$, both including and excluding very massive stars (VMS). Models including VMS provide a markedly improved fit to the data relative to non-VMS models ($Δ$AIC and $Δ$BIC $> 70$), which fail to reproduce the observed strengths of the wind features. A comparison with empirical spectra of VMS-dominated systems in the local Universe further supports this interpretation. The best-fit VMS models imply extremely young ages of the stellar populations ($\simeq 1.5-2.0$Myr) and high ionizing photon production efficiencies ($\log ξ_{\rm ion} [\rm Hz erg^{-1}] \gtrsim 25.8$), exceeding those inferred from non-VMS models by $\sim 0.1-0.2$ dex. These results provide evidence for an overabundance of VMS at high-$z$ with an IMF extending well beyond $100 M_{\odot}$, and highlight their potential role in shaping the rest-frame UV spectra, chemical enrichment, and ionizing output of galaxies in the early Universe. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2604_21493 |
| institution | arXiv |
| publishDate | 2026 |
| record_format | arxiv |
| spellingShingle | Signatures of Very Massive Stars in the Epoch of Reionization Marques-Chaves, Rui Martins, Fabrice Schaerer, Daniel Dessauges-Zavadsky, Miroslava Palacios, Ana Astrophysics of Galaxies Solar and Stellar Astrophysics We present ultra-deep ($\simeq 20-30$ hours), rest-frame UV spectroscopy with NIRSpec/JWST of two UV-bright galaxies at $z\sim 8.7$, CEERS-1019 and CEERS-1025 ($Z_{\rm neb} \simeq 0.1 Z_{\odot}$). The spectra reveal exceptionally strong P-Cygni profiles in wind lines (NV $λ$1240 and CIV $λ$1550) and significant broad and strong HeII $λ$1640 emission ($\rm EW\simeq 2-4$ A). We compare the observations with synthetic stellar population models at $Z_{\star} \simeq 0.1 Z_{\odot}$, both including and excluding very massive stars (VMS). Models including VMS provide a markedly improved fit to the data relative to non-VMS models ($Δ$AIC and $Δ$BIC $> 70$), which fail to reproduce the observed strengths of the wind features. A comparison with empirical spectra of VMS-dominated systems in the local Universe further supports this interpretation. The best-fit VMS models imply extremely young ages of the stellar populations ($\simeq 1.5-2.0$Myr) and high ionizing photon production efficiencies ($\log ξ_{\rm ion} [\rm Hz erg^{-1}] \gtrsim 25.8$), exceeding those inferred from non-VMS models by $\sim 0.1-0.2$ dex. These results provide evidence for an overabundance of VMS at high-$z$ with an IMF extending well beyond $100 M_{\odot}$, and highlight their potential role in shaping the rest-frame UV spectra, chemical enrichment, and ionizing output of galaxies in the early Universe. |
| title | Signatures of Very Massive Stars in the Epoch of Reionization |
| topic | Astrophysics of Galaxies Solar and Stellar Astrophysics |
| url | https://arxiv.org/abs/2604.21493 |