磁星壳层中子海洋的自旋极化
Spin-polarization of the neutron ocean in magnetar crusts
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中文总结 AI 辅助
本研究考虑自由中子自旋极化，发现强磁场会降低磁星内外壳边界处的压力和密度，使外壳变薄、抑制超重核形成并使中子海洋极化，影响磁星现象与r-过程核合成。
中文摘要 AI 辅助
磁星是宇宙中已知磁场最强的中子星，与从巨耀发到快速射电暴等一系列观测现象相关，并被认为是重元素核合成的潜在场所。这些现象被认为与磁星壳层的结构和组成密切相关。磁星外壳由浸在简并电子气体中的完全电离原子核组成，而内壳则额外包含自由中子。我们研究了强磁场如何改变磁星壳层，并考虑了自由中子的自旋极化效应。由于磁场与中子磁矩之间的耦合，中子自旋极化降低了标记外壳与内壳边界的压力和物质密度，当磁场强度 $B \gtrsim 10^{17}~\mathrm{G}$ 时尤为显著。因此，外壳变得更薄，先前研究中预测的超重原子核的形成受到抑制，渗透内壳的中子海洋变得自旋极化。这些效应可能对磁星的多种表现以及磁星巨耀发抛射物中的 $r$-过程核合成产生重要影响。
英文摘要
Magnetars, neutron stars harboring the strongest magnetic fields known in the Universe, are associated with a broad range of observational phenomena, from giant flares to fast radio bursts, and have also been proposed as potential sites of heavy-element nucleosynthesis. These phenomena are thought to be closely linked to the structure and composition of magnetar crusts. The outer crust consists of fully ionized nuclei embedded in a degenerate electron gas, while the inner crust additionally contains free neutrons. We investigate how strong magnetic fields modify magnetar crusts, accounting for the spin polarization of free neutrons. Arising from the coupling between the magnetic field and the neutron magnetic moment, neutron spin polarization lowers both the pressure and matter density marking the boundary between the outer and inner crusts for magnetic field strengths $B \gtrsim 10^{17}~\mathrm{G}$. As a consequence, the outer crust becomes thinner, the formation of the superheavy nuclei predicted in previous studies is suppressed, and the neutron ocean permeating the inner crust becomes spin-polarized. These effects may have important implications for the diverse manifestations of magnetars and for $r$-process nucleosynthesis in the ejecta of magnetar giant flares.
发表机构
- Institute of Astronomy and Astrophysics, Université Libre de Bruxelles（布鲁塞尔自由大学天体物理与天文学研究所）
- Brussels Laboratory of the Universe (BLU-ULB)（宇宙布鲁塞尔实验室）
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