Ia型超新星核合成的启示：来自实验约束的$^{16}$O$(p,α)^{13}$N反应速率的影响
Implications for Type Ia Supernova Nucleosynthesis from an Experimentally Constrained $^{16}$O$(p,α)^{13}$N Reaction Rate
AI总结：
Ia型超新星中，$^{16}$O$(p,α)^{13}$N反应速率的实验约束表明其对Ca/S和Ar/S比值的影响有限，需进一步减少其他关键反应的不确定性以解决金属量差异问题。
摘要：
在Ia型超新星中剧烈氧燃烧过程中，$^{16}$O$(p,α)^{13}$N反应对α粒子丰度的形成起着关键作用。通过增强α粒子的产生，该反应直接影响钙-硫（Ca/S）和氩-硫（Ar/S）比值，这些比值是探测前体金属量的示踪剂。然而，最近的研究表明，为了解释在不同前体金属量范围内观测到的Ca/S比值，该反应的速率必须比标准值提高多达七倍。为探讨这一影响，已收集并批判性评估了可用的实验截面数据。在低能区域（$E_{\mathrm{cm}}$ = 5.7--7.0 MeV）中发现了显著的不一致，这主要是由于激活方法的限制。为了解决这一问题，使用MUSIC主动靶探测器进行了首次在天体物理能量下的直接测量。新的$^{16}$O$(p,α)^{13}$N热核反应速率在温度范围T = 3--4 GK内发现比REACLIB速率大约1.5倍，具有更受约束的不确定性，消除了现有数据中之前较大的分散。所建议的七倍增强因子被排除，这些结果表明该反应单独无法完全解释在不同前体金属量下观察到的Ca/S和Ar/S比值的变化。因此，未来的工作应重点减少其他关键氧燃烧反应的不确定性，特别是$^{16}$O+$^{16}$O和$^{12}$C+$^{16}$O。进一步减少对$^{16}$O$(p,α)^{13}$N速率的约束也是必要的，以完全确定是否存在核物理解决方案来解决这一矛盾。
英文摘要：
The $^{16}$O$(p,α)^{13}$N reaction plays a key role in shaping the $α$-particle abundance during explosive oxygen burning in Type Ia supernovae. By enhancing $α$-production, this reaction directly affects the calcium-to-sulphur (Ca/S) and argon-to-sulphur (Ar/S) ratios, which serves as a tracer of progenitor metallicity. However, recent work suggests that the rate must be enhanced by a factor of up to seven over the standard value to explain observed Ca/S ratios across a range of progenitor metallicities. To explore this impact, available experimental cross-section data for the $^{16}$O$(p,α)^{13}$N reaction have been compiled and critically evaluated. Significant discrepancies are identified in the low-energy region ($E_{\mathrm{cm}}$ = 5.7--7.0 MeV), primarily due to limitations of the activation method. To resolve this, the first direct measurement at astrophysical energies has been performed using the MUSIC active-target detector. The new $^{16}$O$(p,α)^{13}$N thermonuclear reaction rate is found to be approximately 1.5 times higher than the REACLIB rate in the temperature range T = 3--4 GK, with more constrained uncertainties that resolve the previously large spread among existing data. The suggested factor of seven enhancement is excluded and these results indicate that this reaction alone cannot fully explain the variation in the Ca/S and Ar/S ratios observed across different progenitor metallicities. Therefore, future work should focus on reducing the uncertainties in other key oxygen-burning reactions, particularly $^{16}$O+$^{16}$O and $^{12}$C+$^{16}$O. Further reducing the constraints on the $^{16}$O$(p,α)^{13}$N rate is also needed to fully determine to whether a nuclear physics solution to this discrepancy is possible.
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