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arXiv 2006.08803nucl-thastro-ph.SR
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基于有限温度相对论准粒子无规相位近似的恒星电子俘获率

Stellar electron capture rates based on finite temperature relativistic quasiparticle random-phase approximation

A. Ravlic, E. Yuksel, Y. F. Niu, G. Colo, E. Khan, N. Paar

摘要:

电子捕获过程在超新星爆发前的大质量恒星核心坍缩演化中起着重要作用。本文在相对论能量密度泛函框架下,考虑有限温度和核配对效应,描述了恒星环境中电子在核上的俘获。采用有限温度质子-中子准粒子无规相近似和密度依赖的介子交换有效相互作用DD-ME 2计算了相关的核跃迁$J^π= 0^\pm, 1^\pm, 2^\pm$。研究了恒星环境中${}^{44}$ Ti和${}^{56}$ Fe的Gamow-Teller跃迁强度、电子俘获截面和电子俘获率的配对效应和温度效应。据发现,配对相关建立一个额外的解阻塞机制类似于有限温度效应,可以允许否则阻塞单粒子跃迁。在有限温度下包含配对相关可以显着改变电子捕获截面,甚至高达${}^{44}$ Ti的两倍,而对于相同的核电子捕获率可以增加一个以上的数量级。我们的结论是,为了完整地描述电子捕获的核配对和温度效应必须考虑。

英文摘要:

The electron capture process plays an important role in the evolution of the core collapse of a massive star that precedes the supernova explosion. In this study, the electron capture on nuclei in stellar environment is described in the relativistic energy density functional framework, including both the finite temperature and nuclear pairing effects. Relevant nuclear transitions $J^π= 0^\pm, 1^\pm, 2^\pm$ are calculated using the finite temperature proton-neutron quasiparticle random phase approximation with the density-dependent meson-exchange effective interaction DD-ME2. The pairing and temperature effects are investigated in the Gamow-Teller transition strength as well as the electron capture cross sections and rates for ${}^{44}$Ti and ${}^{56}$Fe in stellar environment. It is found that the pairing correlations establish an additional unblocking mechanism similar to the finite temperature effects, that can allow otherwise blocked single-particle transitions. Inclusion of pairing correlations at finite temperature can significantly alter the electron capture cross sections, even up to a factor of two for ${}^{44}$Ti, while for the same nucleus electron capture rates can increase by more than one order of magnitude. We conclude that for the complete description of electron capture on nuclei both pairing and temperature effects must be taken into account.

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