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| Main Authors: | , , , , |
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| Format: | Preprint |
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2025
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| Subjects: | |
| Online Access: | https://arxiv.org/abs/2507.23394 |
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| _version_ | 1866915716250206208 |
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| author | Vícha, Jakub Bakalová, Alena Müller, Ana L. Tkachenko, Olena Stadelmaier, Maximilian K. |
| author_facet | Vícha, Jakub Bakalová, Alena Müller, Ana L. Tkachenko, Olena Stadelmaier, Maximilian K. |
| contents | The mass composition of ultra-high-energy cosmic rays (UHECRs) is usually inferred from the depth of the shower maximum ($X_{\rm{max}}$) of cosmic-ray showers, which is only ambiguously determined by modern hadronic interaction models. We present a data-driven interpretation of UHECRs, the heavy-metal scenario, which assumes pure iron nuclei above $10^{19.6}$ eV ($\approx 40$ EeV) as the heaviest observed mass composition and introduces a global shift in the $X_{\rm{max}}$ scale predicted by the two hadronic interaction models QGSJet II-04 and Sibyll 2.3d. We investigate the consequences of the proposed mass-composition model based on the obtained shifts in the $X_{\rm{max}}$ values, which naturally lead to a heavier mass composition of UHECRs than conventionally assumed. We explore the consequences of our model on the energy evolution of relative fractions of primary species, consequently decomposed energy spectrum, hadronic-interaction studies and the arrival directions of UHECRs. We show that within this scenario, presented recently in Vicha et al 2025 ApJL 986 L34, the cosmic-ray measurements can be interpreted in a more consistent way. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2507_23394 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | A Data-driven Heavy-Metal Scenario for Ultra-High-Energy Cosmic Rays Vícha, Jakub Bakalová, Alena Müller, Ana L. Tkachenko, Olena Stadelmaier, Maximilian K. High Energy Astrophysical Phenomena The mass composition of ultra-high-energy cosmic rays (UHECRs) is usually inferred from the depth of the shower maximum ($X_{\rm{max}}$) of cosmic-ray showers, which is only ambiguously determined by modern hadronic interaction models. We present a data-driven interpretation of UHECRs, the heavy-metal scenario, which assumes pure iron nuclei above $10^{19.6}$ eV ($\approx 40$ EeV) as the heaviest observed mass composition and introduces a global shift in the $X_{\rm{max}}$ scale predicted by the two hadronic interaction models QGSJet II-04 and Sibyll 2.3d. We investigate the consequences of the proposed mass-composition model based on the obtained shifts in the $X_{\rm{max}}$ values, which naturally lead to a heavier mass composition of UHECRs than conventionally assumed. We explore the consequences of our model on the energy evolution of relative fractions of primary species, consequently decomposed energy spectrum, hadronic-interaction studies and the arrival directions of UHECRs. We show that within this scenario, presented recently in Vicha et al 2025 ApJL 986 L34, the cosmic-ray measurements can be interpreted in a more consistent way. |
| title | A Data-driven Heavy-Metal Scenario for Ultra-High-Energy Cosmic Rays |
| topic | High Energy Astrophysical Phenomena |
| url | https://arxiv.org/abs/2507.23394 |