High-entropy ejections from magnetized proto-neutron star winds: implications for heavy element nucleosynthesis
High-entropy ejections from magnetized proto-neutron star winds: implications for heavy element nucleosynthesis
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磁化原中子星风的高熵喷射：对重元素核合成的影响
DOI：
10.1093/mnras/sty480
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发表时间：
2017
影响因子：
4.8
通讯作者：
A. ud
中科院分区：
文献类型：
--
作者：
T. Thompson;A. ud
虽然最初被认为是有希望产生r过程核的，但来自原中子星(Pns)的中微子加热风的标准模型并没有达到产生镧系元素和鳗系元素所需的中子与种子的比率。然而，在PNS风中由r-、Rp-或$up-过程产生的丰度分布敏感地依赖于流动的熵和动力膨胀时间尺度，这可能受到强磁场的强烈影响。在这里，我们给出了从$10^{14}-10^{16}$G的具有强偶极磁场的非旋转中微子加热的PNS风的磁流体动力学模拟结果，并评估了它们在改变核合成条件中的作用。强场在赤道形成封闭区和头盔流光结构，并伴随着环形等离子体中的幕式动力学质量抛射。我们发现，如果风是富中子的，这些区域的熵显著增加，并且有利于第三峰r-过程核合成的条件。如果相反，风是富含质子的，条件将影响$\nu p$-过程的丰度。我们量化了抛射物质在熵和动力学膨胀时间尺度上的分布，以及影响熵所需的临界磁场强度。对于风相高磁化中子星的诞生，我们发现每一颗高磁化的中子星在风相喷发出10-6和高达10-5的高熵物质，为宇宙中重元素的快速浓缩提供了一种机制。在(主存磁星的)超新星残骸中发现的前双星伙伴、残骸本身和逃逸恒星可能会表现出过剩的丰度。我们提供了与等离子体喷发的半解析模型的比较，并讨论了其含义和扩展。
Although initially thought to be promising for production of the r-process nuclei, standard models of neutrino-heated winds from proto-neutron stars (PNSs) do not reach the requisite neutron-to-seed ratio for production of the lanthanides and actinides. However, the abundance distribution created by the r-, rp-, or $\nu p$-processes in PNS winds depends sensitively on the entropy and dynamical expansion timescale of the flow, which may be strongly affected by high magnetic fields. Here, we present results from magnetohydrodynamic simulations of non-rotating neutrino-heated PNS winds with strong dipole magnetic fields from $10^{14}-10^{16}$ G, and assess their role in altering the conditions for nucleosynthesis. The strong field forms a closed zone and helmet streamer configuration at the equator, with episodic dynamical mass ejections in toroidal plasmoids. We find dramatically enhanced entropy in these regions and conditions favorable for third-peak r-process nucleosynthesis if the wind is neutron-rich. If instead the wind is proton-rich, the conditions will affect the abundances from the $\nu p$-process. We quantify the distribution of ejected matter in entropy and dynamical expansion timescale, and the critical magnetic field strength required to affect the entropy. For $B\gtrsim10^{15}$ G, we find that $\gtrsim10^{-6}$ M$_{\odot}$ and up to $\sim10^{-5}$ M$_{\odot}$ of high entropy material is ejected per highly-magnetized neutron star birth in the wind phase, providing a mechanism for prompt heavy element enrichment of the universe. Former binary companions identified within (magnetar-hosting) supernova remnants, the remnants themselves, and runaway stars may exhibit overabundances. We provide a comparison with a semi-analytic model of plasmoid eruption and discuss implications and extensions.
DOI：
10.1111/j.1365-2966.2012.21859.x
发表时间：
2012-11-01
影响因子：
4.8
作者：
Korobkin, O.;Rosswog, S.;Winteler, C.
通讯作者：
Winteler, C.