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題名 紊流混合對快中子捕獲過程(r-process)核合成的影響
Effect of turbulence mixing on R-process nucleosynthesis作者 陳樂仁
Chen, Le-Ren貢獻者 吳孟儒<br>楊志開<br>李尚凡
Meng-Ru Wu<br>Jhih-Kai Yang<br>Shang-Fan Lee
陳樂仁
Chen, Le-Ren關鍵詞 快過程核合成
紊流
中子星合併
短Gamma射線爆(sGRB)
r-process nucleosynthesis
turbulence
neutron stars mergers(NSM)
short gamma-ray burst(sGRB)日期 2021 上傳時間 2021-09-03 摘要 2017 年 8 月雙中子星合併 (BNSM) 事件 GW170817 的重力波和電磁輻射的觀測，不僅標誌著重力波多信使天文學的開始，也提供了不少的證據——證實雙中子星合併是由快中子補獲過程 (r-process 或 快過程) 的不穩定核衰變，來為短γ射線暴 (sGRB) 和千新星提供能量。最近的研究顯示，諸如短γ射線暴噴流穿透雙中子星合併之噴出物的機制，可能會導致噴出物內部大規模的紊流。這種紊流可能會導致噴出物中不同成分，且可能具有不同的核合成條件的流體混合。如果紊流引起的混合發生在快過程期間，與沒有混合的情況相比，它可能會影響快過程的最終產物。在本論文中，我們使用一個簡單的雙流體簡單模型來探討成分混合對雙中子星合併事件中，快過程核合成結果的潛在影響。而我們發現不僅混合本身會改變最終結果，而且混合發生的時間點也會使結果具有不同的狀況。特別是我們發現，如果當其中一流體處在快過程中，而另一種流體已完成其快過程時發生混合，混合效應會導致後者的自由中子的突然增加。因此，它可以幫助在快過程已停止的流體重新啟動快過程；與兩種未混合流體的直接平均值相比，這使得整個系統整體得以生成更重的核素。另一方面，如果當兩種流體仍在快過程中時發生混合，則混合讓兩流體交換其剩餘的自由中子，使高Ye流體獲得更多自由中子進行快過程，而低Ye流體獲得較少的自由中子進行快過程。這將導致兩種流體的最終元素分布彼此接近，並且與在混合系統剛開始時取部分初始Ye平均值非常相似。
The detection of the gravitational wave and electromagnetic emissions from the binary neutron star merger (BNSM) event GW170817 in August 2017 not only marked the beginning of the gravitational-wave multi-messenger astronomy, but also provided evidence that BNSMs are the sources of the short gamma-ray bursts (sGRB) and kilonovae -- transients powered by the decay of unstable nuclei synthesis by the rapid neutron-capture process (r-process).Recent studies suggested that mechanisms such as the sGRB jet penetrating the BNSM ejecta may result in large-scale turbulence inside the ejecta. Such turbulence can possibly cause composition mixing of different fluid components inside the ejecta, which might have different nucleosynthesis conditions. If the mixing caused by the turbulence happens during r-process, it may affect the resulting r-process yield predictions when compared to cases without mixing.In this thesis, we use a simple two-fluid toy-model to study the impact of a potential composition mixing on the r-process nucleosynthesis outcome in BNSM events. We find that not only mixing itself will alter the final result, but also the time that mixing happen will make the result have different shape.In particular, we find that if mixings happen when one of fluids is within the r-process while the other one has finished its r-process, mixing effect leads to sudden increase of free neutrons in the latter. Thus, it can help re-start the r-process in the fluid wherein the r-process had ceased. This allows the whole system to produce overall heavier nuclei when compared to the direct average of two unmixed fluids.On the other hand, if mixings occur when both fluids are still within the r-process, then mixing let both fluids exchange their remaining free neutrons, make high $Y_e$ fluid get more free neutron to r-process, and low $Y_e$ fluid get lesser free neutron to r-process, where $Y_e\\equiv n_e/n_b$, and $n_e$ ($n_b$) is the electron (baryon) number density. This will cause both fluids` final abundance distribution getting close toward each other, and it pretty similar to take a partial initial $Y_e$ averaging at begin of mixing system.參考文獻 [Abbott et al., 2017a] Abbott, B., Abbott, R., Abbott, T., Acernese, F., Ackley, K.,Adams, C., Adams, T., Addesso, P., Adhikari, R., Adya, V., and et al. (2017a).Gw170817: Observation of gravitational waves from a binary neutron star inspiral.Physical Review Letters, 119(16).[Abbott et al., 2017b] Abbott, B. P., Abbott, R., Abbott, T. D., Acernese, F., Ack-ley, K., Adams, C., Adams, T., Addesso, P., Adhikari, R. X., Adya, V. B., andet al. (2017b). Multi-messenger observations of a binary neutron star merger. TheAstrophysical Journal, 848(2):L12.[Cowan et al., 2021] Cowan, J. J., Sneden, C., Lawler, J. E., Aprahamian, A., Wi-escher, M., Langanke, K., Martinez-Pinedo, G., and Thielemann, F.-K. (2021).Origin of the heaviest elements: The rapid neutron-capture process. Reviews ofModern Physics, 93(1).[Domoto et al., 2021] Domoto, N., Tanaka, M., Wanajo, S., and Kawaguchi, K.(2021). Signatures of r-process elements in kilonova spectra. The AstrophysicalJournal, 913(1):26.[Giuliani et al., 2020] Giuliani, S. A., Martinez-Pinedo, G., Wu, M.-R., and Rob-ledo, L. M. (2020). Fission and the r -process nucleosynthesis of translead nucleiin neutron star mergers. Physical Review C, 102(4).[Hamidani and Ioka, 2020] Hamidani, H. and Ioka, K. (2020). Jet propagation inexpanding medium for gamma-ray bursts. Monthly Notices of the Royal Astro-nomical Society, 500(1):627{642.[Hamidani et al., 2019] Hamidani, H., Kiuchi, K., and Ioka, K. (2019). Jet prop-agation in neutron star mergers and gw170817. Monthly Notices of the RoyalAstronomical Society.[Wu et al., 2019] Wu, M.-R., Barnes, J., Martinez-Pinedo, G., and Metzger, B.(2019). Fingerprints of heavy-element nucleosynthesis in the late-time lightcurvesof kilonovae. Physical Review Letters, 122(6).32 描述 碩士
國立政治大學
應用物理研究所
108755006資料來源 http://thesis.lib.nccu.edu.tw/record/#G0108755006 資料類型 thesis dc.contributor.advisor 吳孟儒<br>楊志開<br>李尚凡 zh_TW dc.contributor.advisor Meng-Ru Wu<br>Jhih-Kai Yang<br>Shang-Fan Lee en_US dc.contributor.author (作者) 陳樂仁 zh_TW dc.contributor.author (作者) Chen, Le-Ren en_US dc.creator (作者) 陳樂仁 zh_TW dc.creator (作者) Chen, Le-Ren en_US dc.date (日期) 2021 en_US dc.date.accessioned 2021-09-03 - dc.date.available 2021-09-03 - dc.date.issued (上傳時間) 2021-09-03 - dc.identifier (其他 識別碼) G0108755006 en_US dc.identifier.uri (URI) http://nccur.lib.nccu.edu.tw/handle/140.119/137207 - dc.description (描述) 碩士 zh_TW dc.description (描述) 國立政治大學 zh_TW dc.description (描述) 應用物理研究所 zh_TW dc.description (描述) 108755006 zh_TW dc.description.abstract (摘要) 2017 年 8 月雙中子星合併 (BNSM) 事件 GW170817 的重力波和電磁輻射的觀測，不僅標誌著重力波多信使天文學的開始，也提供了不少的證據——證實雙中子星合併是由快中子補獲過程 (r-process 或 快過程) 的不穩定核衰變，來為短γ射線暴 (sGRB) 和千新星提供能量。最近的研究顯示，諸如短γ射線暴噴流穿透雙中子星合併之噴出物的機制，可能會導致噴出物內部大規模的紊流。這種紊流可能會導致噴出物中不同成分，且可能具有不同的核合成條件的流體混合。如果紊流引起的混合發生在快過程期間，與沒有混合的情況相比，它可能會影響快過程的最終產物。在本論文中，我們使用一個簡單的雙流體簡單模型來探討成分混合對雙中子星合併事件中，快過程核合成結果的潛在影響。而我們發現不僅混合本身會改變最終結果，而且混合發生的時間點也會使結果具有不同的狀況。特別是我們發現，如果當其中一流體處在快過程中，而另一種流體已完成其快過程時發生混合，混合效應會導致後者的自由中子的突然增加。因此，它可以幫助在快過程已停止的流體重新啟動快過程；與兩種未混合流體的直接平均值相比，這使得整個系統整體得以生成更重的核素。另一方面，如果當兩種流體仍在快過程中時發生混合，則混合讓兩流體交換其剩餘的自由中子，使高Ye流體獲得更多自由中子進行快過程，而低Ye流體獲得較少的自由中子進行快過程。這將導致兩種流體的最終元素分布彼此接近，並且與在混合系統剛開始時取部分初始Ye平均值非常相似。 zh_TW dc.description.abstract (摘要) The detection of the gravitational wave and electromagnetic emissions from the binary neutron star merger (BNSM) event GW170817 in August 2017 not only marked the beginning of the gravitational-wave multi-messenger astronomy, but also provided evidence that BNSMs are the sources of the short gamma-ray bursts (sGRB) and kilonovae -- transients powered by the decay of unstable nuclei synthesis by the rapid neutron-capture process (r-process).Recent studies suggested that mechanisms such as the sGRB jet penetrating the BNSM ejecta may result in large-scale turbulence inside the ejecta. Such turbulence can possibly cause composition mixing of different fluid components inside the ejecta, which might have different nucleosynthesis conditions. If the mixing caused by the turbulence happens during r-process, it may affect the resulting r-process yield predictions when compared to cases without mixing.In this thesis, we use a simple two-fluid toy-model to study the impact of a potential composition mixing on the r-process nucleosynthesis outcome in BNSM events. We find that not only mixing itself will alter the final result, but also the time that mixing happen will make the result have different shape.In particular, we find that if mixings happen when one of fluids is within the r-process while the other one has finished its r-process, mixing effect leads to sudden increase of free neutrons in the latter. Thus, it can help re-start the r-process in the fluid wherein the r-process had ceased. This allows the whole system to produce overall heavier nuclei when compared to the direct average of two unmixed fluids.On the other hand, if mixings occur when both fluids are still within the r-process, then mixing let both fluids exchange their remaining free neutrons, make high $Y_e$ fluid get more free neutron to r-process, and low $Y_e$ fluid get lesser free neutron to r-process, where $Y_e\\equiv n_e/n_b$, and $n_e$ ($n_b$) is the electron (baryon) number density. This will cause both fluids` final abundance distribution getting close toward each other, and it pretty similar to take a partial initial $Y_e$ averaging at begin of mixing system. en_US dc.description.tableofcontents Contents1 Introduction 32 Physical Model 62.1 Parameter set-up . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62.1.1 Initial electron fraction selection Ye . . . . . . . . . . . . . . . 72.1.2 The duration of mixing Td . . . . . . . . . . . . . . . . . . . . 72.1.3 Mixing times Nm . . . . . . . . . . . . . . . . . . . . . . . . . 72.1.4 Exchanging effciency with in mixing duration Fm,fm . . . . . 82.2 Program implementation . . . . . . . . . . . . . . . . . . . . . . . . . 103 Result Analysis and Discussion 123.1 Evolving singleuid without mixing . . . . . . . . . . . . . . . . . . 123.2 Complete mixing for twouids system . . . . . . . . . . . . . . . . . 133.3 Incomplete mixing for twouids system . . . . . . . . . . . . . . . . 183.3.1 Mixing with Fm = 50% - halved mixing . . . . . . . . . . . . . 193.3.2 Mixing with Fm = 80% . . . . . . . . . . . . . . . . . . . . . . 234 Conclusion and Outlook 284.1 Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 284.2 Outlook . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29Reference 31 zh_TW dc.format.extent 1094646 bytes - dc.format.mimetype application/pdf - dc.source.uri (資料來源) http://thesis.lib.nccu.edu.tw/record/#G0108755006 en_US dc.subject (關鍵詞) 快過程核合成 zh_TW dc.subject (關鍵詞) 紊流 zh_TW dc.subject (關鍵詞) 中子星合併 zh_TW dc.subject (關鍵詞) 短Gamma射線爆(sGRB) zh_TW dc.subject (關鍵詞) r-process nucleosynthesis en_US dc.subject (關鍵詞) turbulence en_US dc.subject (關鍵詞) neutron stars mergers(NSM) en_US dc.subject (關鍵詞) short gamma-ray burst(sGRB) en_US dc.title (題名) 紊流混合對快中子捕獲過程(r-process)核合成的影響 zh_TW dc.title (題名) Effect of turbulence mixing on R-process nucleosynthesis en_US dc.type (資料類型) thesis en_US dc.relation.reference (參考文獻) [Abbott et al., 2017a] Abbott, B., Abbott, R., Abbott, T., Acernese, F., Ackley, K.,Adams, C., Adams, T., Addesso, P., Adhikari, R., Adya, V., and et al. (2017a).Gw170817: Observation of gravitational waves from a binary neutron star inspiral.Physical Review Letters, 119(16).[Abbott et al., 2017b] Abbott, B. P., Abbott, R., Abbott, T. D., Acernese, F., Ack-ley, K., Adams, C., Adams, T., Addesso, P., Adhikari, R. X., Adya, V. B., andet al. (2017b). Multi-messenger observations of a binary neutron star merger. TheAstrophysical Journal, 848(2):L12.[Cowan et al., 2021] Cowan, J. J., Sneden, C., Lawler, J. E., Aprahamian, A., Wi-escher, M., Langanke, K., Martinez-Pinedo, G., and Thielemann, F.-K. (2021).Origin of the heaviest elements: The rapid neutron-capture process. Reviews ofModern Physics, 93(1).[Domoto et al., 2021] Domoto, N., Tanaka, M., Wanajo, S., and Kawaguchi, K.(2021). Signatures of r-process elements in kilonova spectra. The AstrophysicalJournal, 913(1):26.[Giuliani et al., 2020] Giuliani, S. A., Martinez-Pinedo, G., Wu, M.-R., and Rob-ledo, L. M. (2020). Fission and the r -process nucleosynthesis of translead nucleiin neutron star mergers. Physical Review C, 102(4).[Hamidani and Ioka, 2020] Hamidani, H. and Ioka, K. (2020). Jet propagation inexpanding medium for gamma-ray bursts. Monthly Notices of the Royal Astro-nomical Society, 500(1):627{642.[Hamidani et al., 2019] Hamidani, H., Kiuchi, K., and Ioka, K. (2019). Jet prop-agation in neutron star mergers and gw170817. Monthly Notices of the RoyalAstronomical Society.[Wu et al., 2019] Wu, M.-R., Barnes, J., Martinez-Pinedo, G., and Metzger, B.(2019). Fingerprints of heavy-element nucleosynthesis in the late-time lightcurvesof kilonovae. Physical Review Letters, 122(6).32 zh_TW dc.identifier.doi (DOI) 10.6814/NCCU202101441 en_US
