论文标题
关于积聚与螺旋桨状态之间过渡的磁滞效应
On the hysteresis effect in transitions between accretion and propeller regimes
论文作者
论文摘要
圆盘磁层相互作用的一些观察结果和数值模拟表明，螺旋桨状态可以进行增值。当alfvén半径超出了旋转半径，物质会爬到alfvén表面在平衡表面内部并可以吸收的高纬度。我们计算圆盘中质量通量的分数，该量可以根据固定参数以及旋转和磁轴之间的倾斜角来吸收中子恒星。我们发现，对于固定参数的狭窄范围，alfvén和平衡表面在两个不同的临界纬度上相交。虽然系统从螺旋桨转到积聚方案（爆发的初始上升），但盘已经厚，并且这两个临界纬度之间的光盘部分无法吸收。在从积聚到螺旋桨状态（爆发的衰减）的过渡中，椎间盘很薄，因此，物质的全部积聚会继续进行，直到Alfvén半径超出了圆盘中间的平衡半径。因此，积聚制度的牢固性参数比停止的牢固度参数较小。结果，从螺旋桨到增生方案的过渡发生的光度高于从吸积到螺旋桨状态的过渡。我们讨论了我们的结果对低质量X射线二进制文件所表现出的光谱转变的含义。
Some observations and numerical simulations of disc-magnetosphere interaction show that accretion can proceed in the propeller regime. When the Alfvén radius is beyond the corotation radius, matter climbs up to the high latitudes where the Alfvén surface is inside the equilibrium surface and can accrete. We calculate the fraction of the mass flux in the disc that can accrete onto the neutron star depending on the fastness parameter and the inclination angle between rotation and magnetic axis. We find that, for a narrow range of the fastness parameter, the Alfvén and the equilibrium surfaces intersect at two different critical latitudes. While the system is transiting from the propeller to the accretion regime (the initial rise of an outburst), the disc is already thick and the part of the disc between these two critical latitudes cannot accrete. In transitions from the accretion to the propeller regime (decay of an outburst), the disc is thin, hence, full accretion of matter proceeds until the Alfvén radius moves beyond the equilibrium radius at the disc-midplane. Therefore, the accretion regime commences at a smaller fastness parameter than it ceases. As a result, the transition from the propeller to the accretion regime occurs at a luminosity higher than the transition from the accretion to the propeller regime. We discuss the implications of our results for spectral transitions exhibited by low-mass X-ray binaries.
