过渡毫秒脉冲星中的模式：来自广义相对论磁流体动力学和辐射转移的脉冲星风致盘加热的证据
Modes in Transitional Millisecond Pulsars: Evidence of Pulsar Wind-Induced Disk Heating from GRMHD and Radiative Transfer
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中文总结 AI 辅助
研究过渡毫秒脉冲星X射线发射源，通过广义相对论磁流体动力学模拟及辐射转移代码后处理，探索不同盘状态，发现风致盘加热在高低X射线模式中均有贡献，解释了相关现象并与观测相符。
中文摘要 AI 辅助
过渡毫秒脉冲星（tMSPs）在射电和X射线脉冲星状态之间交替，可能是旋转驱动和吸积驱动中子星之间缺失的环节。其盘状态在低和高X射线模式之间随机切换，物理起源不明且比低质量X射线双星亮度低。为揭示X射线发射源，进行了吸积盘与tMSP磁层相互作用的二维轴对称广义相对论磁流体动力学模拟，并首次用包含热同步辐射、吸收和康普顿散射过程的辐射转移代码对模拟进行后处理。通过改变盘密度和流入率，探索了两种盘状态：一种在光筒外截断，另一种在光筒内。在前一种状态下，大部分X射线通量来自风加热盘产生的同步辐射，可能对应高X射线模式；后一种是螺旋桨状态，缺乏这种加热过程，但螺旋桨会间歇性地排出盘，激活风加热，70%-30%的螺旋桨和风状态混合物可再现低X射线模式的X射线光谱。螺旋桨状态下多余的电磁转矩使两种模式平均的自旋-down率比无盘射电脉冲星状态高出百分之几，与观测一致。总体而言，当流在光筒外截断时，系统在X射线中更亮，且在低和高X射线模式中都支持风致盘加热的贡献。
英文摘要
Transitional millisecond pulsars (tMSPs) alternate between radio and X-ray pulsar states, and can represent the missing link between rotation- and accretion-powered neutron stars. Their disk state switches stochastically between the low and high X-ray modes, both of unknown physical origin and less luminous than low-mass X-ray binaries. To reveal the source of the X-ray emission, we carry out 2D axisymmetric general-relativistic magnetohydrodynamical simulations of the interaction between an accretion disk and tMSP magnetosphere. For the first time, we post-process tMSP simulations with a radiative transfer code that incorporates thermal synchrotron, absorption, and Compton scattering processes. By varying the disk density, hence the inflow rate, we explore two disk regimes: one truncated outside and another inside the light cylinder. In the former, most of the X-ray flux comes from the synchrotron emission powered by the wind heating the disk: this "wind" regime could correspond to the high X-ray mode. The latter is the propeller regime and lacks this heating process. However, the propeller episodically expels the disk, activating the wind heating: a 70%-30% mixture of such propeller and wind regimes reproduces the X-ray spectrum of the low X-ray mode. The excess electromagnetic torque in the propeller regime increases the spin-down rate, averaged over both modes, by a few percent above the disk-free radio pulsar state, in agreement with observations. Overall, the system is more luminous in X-rays when the flow is truncated outside the light cylinder and supports a contribution from wind-induced disk heating in both low and high X-ray modes.
