AI 中文总结
研究奇特长伽马射线暴起源，基于中子星-白矮星合并及磁星巨型耀斑，提出统一图景。通过超吸积放大磁场触发耀斑，解释瞬时发射各阶段，火球冲击地壳合成重元素解决r过程亏损，还能解释千新星及X射线平台，提供自洽框架。
AI 中文摘要
以GRBs 211211A和230307A为代表的奇特长伽马射线暴，呈现出长时间多成分瞬时发射、余辉中的X射线平台以及千新星特征，其起源备受争议。本文基于涉及合并前磁星和大质量白矮星的中子星-白矮星合并，给出了这些事件的统一图景。白矮星的潮汐瓦解形成等熵吸积盘，早期吸积阶段盘对中子星的超吸积将其环形磁场放大到足以触发磁星巨型耀斑的强度。瞬时发射的主暴由这些耀斑的初始尖峰组成，随后的磁螺旋桨阶段产生延展发射并解释了主暴-延展发射低谷。每个耀斑初始尖峰的正负电子-伽马火球冲击中子星地壳，导致地壳物质喷射，通过富α冻结机制合成r过程重元素，解决了传统中子星-白矮星流体动力学模拟中的r过程亏损问题。主暴持续时间内这些火球的集合产生了质量约为10^-5 - 10^-3太阳质量的抛射物，合并后磁星的自旋-down进一步增强，足以驱动观测到的千新星特征。同时，自旋-down辐射也为X射线平台提供能量。这种潮汐瓦解的中子星-白矮星合并图景为奇特长伽马射线暴中观测到的瞬时发射、余辉、千新星和r过程核合成提供了一个自洽的框架。
英文摘要
Peculiar long gamma-ray bursts (GRBs), exemplified by GRBs 211211A and 230307A, exhibit a long-duration multi-component prompt emission, an X-ray plateau in their afterglow, and a kilonova signature. Their origin remains highly debated. In this work, we present a unified picture for these events based on neutron star--white dwarf (NS--WD) mergers involving a pre-merger magnetar and a massive WD. In this picture, tidal disruption of the WD forms a constant-entropy accretion disk. Hyperaccretion from this disk onto the NS during the early accretion phase amplifies its toroidal magnetic field to strengths sufficient to trigger repeated magnetar giant flares (GFs). The main burst (MB) of the prompt emission consists of a ``forest'' of initial spikes from these GFs, while the subsequent magnetic propeller phase generates the extended emission (EE) and naturally explains the observed MB--EE trough. Crucially, the $e^{\pm}$-$γ$ fireball associated with each GF initial spike shocks the NS crust, leading to crustal ejection that synthesizes r-process heavy elements via the $α$-rich freeze-out mechanism, thereby resolving the r-process deficit in conventional NS--WD hydrodynamic simulations. The ensemble of such fireballs over the MB duration collectively yields $M_{\rm ej}\gtrsim 10^{-5}-10^{-3}\,M_\odot$ of ejecta, sufficient to power the observed kilonova signature when further boosted by the spin-down of the post-merger magnetar. Meanwhile, the spin-down radiation also powers the X-ray plateau. This tidally disrupted NS--WD merger picture provides a self-consistent framework that unifies the prompt emission, afterglow, kilonova, and r-process nucleosynthesis observed in peculiar long GRBs.
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