旋转大质量包层内的超吸积磁化中子星：低功率喷流与前兆耀斑
Hyperaccreting Magnetised Neutron Stars inside Rotating Massive Envelopes: Low-Power Jets and Precursor Flares
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中文总结 AI 辅助
本研究通过GRMHD模拟，探究旋转大质量包层内超吸积磁化中子星的演化，发现强表面磁场可延迟黑洞形成并产生低功率前兆喷流，但无法剥离包层。
中文摘要 AI 辅助
大质量伴星吞噬中子星（NS）会启动高度动态的公共包层（CE）演化阶段。当中子星螺旋进入致密恒星核心时，会承受超临界吸积率，这可能迅速将中子星坍缩为黑洞（BH）。然而，若下落包层具有足够角动量和磁场，中子星可能存活更久并驱动反馈喷流。为研究该问题，研究人员开展了完全耦合的轴对称广义相对论磁流体动力学（GRMHD）模拟，模拟对象为超吸积中子星，包含能量积分两中微子矩传输和13同位素核反应网络。研究系统改变了包层旋转轮廓和中子星表面磁场强度（$B_{\rm surf} \backsim 5 \times 10^{10} - 5 \times 10^{13}$ G）。在非磁化模型中，发现包层旋转自然形成离心屏障和几何厚吸积盘，这会抑制质量吸积率并降低中微子光度；相反，中子星的本征自旋无全局影响。在磁化模型中，吸积流的较差旋转通过Ω效应剧烈放大环形磁场，驱动磁塔膨胀。关键的是，对于强初始表面磁场（$B_{\rm surf} \backsim 2.3 \times 10^{13}$ G），强磁压可完全在中子星表面阻止吸积流并排空低密度极向漏斗。研究得出结论，这种高磁化中子星引擎虽成功延迟即时黑洞形成，且可能发射功率约$10^{46}$ erg/s的低功率前兆喷流，可产生可观测X射线耀斑，但它缺乏能量预算来剥离大质量包层，为后续黑洞驱动爆炸奠定了基础。
英文摘要
The engulfment of a neutron star (NS) by a massive companion initiates a highly dynamic common-envelope (CE) evolution phase. As the NS spirals into the dense stellar core, it is subjected to hypercritical accretion rates that threaten to rapidly collapse the NS into a black hole (BH). However, if the infalling envelope possesses sufficient angular momentum and magnetic fields, the NS might survive longer and launch feedback-driving jets. To investigate this, we perform fully coupled, axisymmetric General Relativistic Magnetohydrodynamic (GRMHD) simulations of hyperaccreting NSs, featuring energy-integrated two-moment neutrino transport and a 13-isotope nuclear reaction network. We systematically vary the envelope rotation profile and the magnetic field strength of the NS surface ($B_{\rm surf} \sim 5 \times 10^{10} - 5 \times 10^{13}$~G). In non-magnetised models, we find that envelope rotation naturally forms a centrifugal barrier and a geometrically thick accretion disk, which suppresses the mass accretion rate and lowers the neutrino luminosity; conversely, the intrinsic spin of the NS has a negligible global impact. In magnetised models, the differential rotation of the accretion flow vigorously amplifies the toroidal magnetic field via the $Ω$-effect, driving the expansion of magnetic towers. Crucially, for strong initial surface magnetic fields ($B_{\rm surf} \gtrsim 2.3 \times 10^{13}$~G), the intense magnetic pressure could completely halt the accretion flow at the NS surface and evacuates a low-density polar funnel. We conclude that while this highly magnetised NS engine successfully delays prompt BH formation and may launche low-power precursor jets (with powers up to ${\sim} 10^{46}~{\rm erg/s}$) capable of generating observable X-ray flares, it lacks the energy budget to unbind the massive envelope, setting the stage for a subsequent BH-driven explosion.
