Unraveling the anomaly in the production of $^{60}$Fe nucleus in massive stars
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arXiv
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| Autori principali: | , , , , , , , , |
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| Natura: | Preprint |
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2025
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| _version_ | 1866909968585719808 |
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| author | Lakshan, Samapti Phuc, Le Tan Pandit, Deepak Bhattacharya, Srijit Huong, Le Thi Quynh Dang, Nguyen Dinh Dey, Balaram Anh, Nguyen Ngoc Hung, Nguyen Quang |
| author_facet | Lakshan, Samapti Phuc, Le Tan Pandit, Deepak Bhattacharya, Srijit Huong, Le Thi Quynh Dang, Nguyen Dinh Dey, Balaram Anh, Nguyen Ngoc Hung, Nguyen Quang |
| contents | The production of $^{60}$Fe is crucial for nucleosynthesis in massive stars and supernovae. In this work, by using the microscopic EP+IPM (exact pairing plus the independent-particle model) for the nuclear level density (NLD) and extended EP+PDM (exact pairing plus phonon damping model) for the $γ$-ray strength function (gSF), we re-evaluate the substantial enhancement of $^{60}$Fe production recently reported in {\it A. Spyrou et al., Nat. Comm. {\bf 15}, 9608 (2024)}, which was attributed to an unexpectedly large Maxwellian-averaged cross section (MACS). Our analysis demonstrates that this enhancement indeed originates from the choice of NLD, which, despite being constrained to reproduce the total NLD and gSF data, lacks a reliable spin dependence, a critical input for Hauser-Feshbach calculations of nuclear reaction rate. In contrast, our predictions yield a significantly lower MACS, calling the claimed enhancement into question. In particular, our approach highlights the microscopic nature of the low-energy enhancement of the gSF, the so-called upbend resonance, which arises from strong particle-particle ($pp$) and hole-hole ($hh$) excitations that emerge only at finite temperature, thereby further reinsisting on the invalidity of the Brink-Axel hypothesis in this low-energy region. Overall, our study reopens the question on the long-standing problem of $^{60}$Fe production in massive stars. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2512_16130 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Unraveling the anomaly in the production of $^{60}$Fe nucleus in massive stars Lakshan, Samapti Phuc, Le Tan Pandit, Deepak Bhattacharya, Srijit Huong, Le Thi Quynh Dang, Nguyen Dinh Dey, Balaram Anh, Nguyen Ngoc Hung, Nguyen Quang Nuclear Theory High Energy Astrophysical Phenomena Solar and Stellar Astrophysics The production of $^{60}$Fe is crucial for nucleosynthesis in massive stars and supernovae. In this work, by using the microscopic EP+IPM (exact pairing plus the independent-particle model) for the nuclear level density (NLD) and extended EP+PDM (exact pairing plus phonon damping model) for the $γ$-ray strength function (gSF), we re-evaluate the substantial enhancement of $^{60}$Fe production recently reported in {\it A. Spyrou et al., Nat. Comm. {\bf 15}, 9608 (2024)}, which was attributed to an unexpectedly large Maxwellian-averaged cross section (MACS). Our analysis demonstrates that this enhancement indeed originates from the choice of NLD, which, despite being constrained to reproduce the total NLD and gSF data, lacks a reliable spin dependence, a critical input for Hauser-Feshbach calculations of nuclear reaction rate. In contrast, our predictions yield a significantly lower MACS, calling the claimed enhancement into question. In particular, our approach highlights the microscopic nature of the low-energy enhancement of the gSF, the so-called upbend resonance, which arises from strong particle-particle ($pp$) and hole-hole ($hh$) excitations that emerge only at finite temperature, thereby further reinsisting on the invalidity of the Brink-Axel hypothesis in this low-energy region. Overall, our study reopens the question on the long-standing problem of $^{60}$Fe production in massive stars. |
| title | Unraveling the anomaly in the production of $^{60}$Fe nucleus in massive stars |
| topic | Nuclear Theory High Energy Astrophysical Phenomena Solar and Stellar Astrophysics |
| url | https://arxiv.org/abs/2512.16130 |