AI 中文总结
本研究提出带喷流的微潮汐瓦解事件（micro-TDE）作为超长伽马射线暴（ULGRB）的引擎，通过三维流体动力学模拟解释了GRB250702B的X射线 precursor、超长瞬时辐射及数周衰减的多阶段演化。
AI 中文摘要
已探测到的最长伽马射线暴GRB250702B表现出7小时的瞬时γ射线辐射，此前约1天出现软X射线 precursor，之后伴随数周的衰减X射线尾。由于缺乏能解释这三个阶段的确定前身天体，我们提出该超长伽马射线暴（ULGRB）由带喷流的微潮汐瓦解事件（micro-TDE）驱动，其中一个自旋的恒星质量黑洞（BH）瓦解一颗类太阳恒星，并通过Blandford-Znajek机制产生相对论喷流。微-TDE debris盘的黏滞时标为小时到天量级，自然解释了ULGRB的持续时间。通过使用AREPO三维流体动力学模拟，模拟10倍太阳质量（10 M☉）黑洞瓦解1倍太阳质量（1 M☉）恒星的过程，我们发现约1天内， debris形成准稳态包层，其中存在低密度极区漏斗（密度ρ∝r⁻²，半开角约15°）。将解析喷流稳定性框架应用于这些剖面，我们发现r⁻²型漏斗使喷流保持在扭结不稳定性阈值以下，当喷流功率L_jet≥10⁴⁷ erg s⁻¹时，喷流可稳定传播并突破。我们将X射线 precursor归因于预盘流供能的吸积；瞬时GRB归因于由快速自旋黑洞（a_•≈0.9）驱动的窄束喷流（束半角θ_b≲1°，各向同性能L_γ,iso≈10⁵¹ erg s⁻¹）从漏斗中逃逸；数周的X射线衰减归因于盘风质量损失（L_jet∝t⁻²）结合喷流展宽（θ_b∝t，初始使衰减变陡为L_X,iso∝L_jet/θ_b²∝t⁻⁴）。我们的模型再现了GRB250702B的多阶段演化，并确立带喷流的微-TDE是具有物理依据的ULGRB引擎。
英文摘要
The longest detected gamma-ray burst, GRB250702B, exhibited seven hours of prompt $γ$-ray emission, preceded by a soft X-ray precursor ($\sim1$ day earlier) and followed by a weeks-long fading X-ray tail. Lacking an established progenitor for all three phases, we propose that this ultra-long GRB (ULGRB) is powered by a jetted micro-tidal disruption event (micro-TDE), in which a spinning stellar-mass black hole (BH) disrupts a Sun-like star and launches a relativistic jet via the Blandford-Znajek mechanism. Micro-TDE debris disks have hours-to-days viscous timescales, naturally explaining ULGRB durations. Using 3D hydrodynamic AREPO simulations of a $1\,M_\odot$ star disrupted by a $10\,M_\odot$ BH, we show that within $\sim1$ day the debris forms a quasi-steady envelope with a low-density polar funnel ($ρ\propto r^{-2}$, half-opening angle $\approx15^\circ$). Applying an analytic jet-stability framework to these profiles, we find that the $r^{-2}$ funnel keeps the jet below the kink-instability threshold, enabling stable propagation and breakout for jet powers, $L_{\rm jet}\gtrsim10^{47}$ erg s$^{-1}$. We attribute the X-ray precursor to pre-disk stream-fed accretion; the prompt GRB to a tightly beamed jet ($θ_{\rm b}\lesssim1^\circ$, $L_{γ,\rm iso}\sim10^{51}$ erg s$^{-1}$) escaping the funnel, launched by a rapidly spinning BH ($a_\bullet\sim0.9$); and the weeks-long X-ray decline to disk-wind mass loss ($L_{\rm jet}\propto t^{-2}$) combined with jet widening ($θ_{\rm b}\propto t$, initially steepening the decay to $L_{\rm X,iso}\propto L_{\rm jet}/θ_{\rm b}^{2}\propto t^{-4}$). Our model reproduces the multi-phase evolution of GRB250702B and establishes jetted micro-TDEs as a physically motivated ULGRB engine.
Comments16 pages, 6 figures, submitted to ApJL
