标题： 磁化中子星吸积：从光子俘获到中微子冷却的流 显示英文标题

标题： Magnetized Accretion onto Neutron Stars: from Photon-trapped to Neutrino-cooled Flows

摘要： 当中子星（NS）拦截来自非简并星的气体时，例如在潮汐破坏事件、共同包层阶段或大质量恒星的核心坍缩过程中，光子被困在围绕NS的热流中。 这些气体会形成一个辐射低效吸积流（RIAF），直到接近NS表面的密度和温度变得足够高，使得结合能可以转换为中微子。 在这里，我们提出了对一个不旋转且未磁化的NS的吸积过程的三维广义相对论磁流体力学模拟。 这些模拟首次将延伸的吸积盘与恒星周围的自洽流体静力学大气层连接起来。 通过将辐射压力主导的流动近似为一种绝热指数为$4/3$的理想气体，并将其与可变的中微子发射率耦合，研究了不同的种子磁场和吸积率的影响。 在低吸积率下，流体静力学大气层显示出缓慢的旋转和弱磁化，过渡到外层的RIAF结构。 环向磁场通过大气层调节能量和角动量的向内流动，在中微子发射平衡吸积功率时达到稳定状态。 我们开发了一个一维解析模型，将这些结果与更一般的初始条件联系起来，并描述了流动的主要特征。 我们的结果对超临界吸积NS的自旋和质量演化具有影响。 显示英文摘要

摘要： When a neutron star (NS) intercepts gas from a non-degenerate star, e.g., in a tidal disruption event, a common-envelope phase, or the collapsing core of a massive star, photons become trapped in the hot flow around the NS. This gas forms a radiatively inefficient accretion flow (RIAF) until the density and temperature close to the NS surface grow large enough for binding energy to be converted to neutrinos. Here we present three-dimensional, general-relativistic, magnetohydrodynamic simulations of accretion onto a non-rotating, unmagnetized NS. These connect, for the first time, an extended accretion disk with a self-consistent hydrostatic atmosphere around the star. The impact of different seed magnetic fields and accretion rates is studied by approximating the radiation-pressure dominated flow as an ideal gas with an adiabatic index of $4/3$, coupled to a variable neutrino emissivity. At low accretion rates, the hydrostatic atmosphere shows slow rotation and weak magnetization, transitioning to an outer RIAF structure. A toroidal magnetic field mediates the inward flow of energy and angular momentum through the atmosphere, which reaches a steady state when neutrino emission balances the accretion power. We develop a one-dimensional analytical model connecting these results with more general initial conditions and describing the main features of the flow. Our results have implications for the spin and mass evolution of hypercritically accreting NSs.