Magnetic fields of strongly magnetized stars can trap conducting matter due to frozen-in condition. In the force-free regime, the motion of the matter along the field lines may be considered in the "bead on a wire" approximation. Such a motion, if gravity and centrifugal forces are taken into account, has equilibrium points, some of which are stable. In most cases, stability is possible in about several per cent of the possible locations. Corresponding oscillation frequencies span the range from zero to $\sqrt{3}$ of the spin frequency. We suggest that this variability mode may be excited in some X-ray pulsars during the outbursts and create the peaked broad-band noise component near the break frequency in the power density spectrum, as well as produce some of the quasi-periodic oscillation features in this frequency range. Existence of this variability does not require any changes in mass accretion rate and involves only a small amount of matter infiltrating from the disc and magnetic flow due to interchange instabilities.

中文翻译：

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倾斜偶极磁层的惯性振荡模式作为 X 射线脉冲星中带限噪声的来源

由于冻结条件，强磁化恒星的磁场可以捕获导电物质。在无力状态下，物质沿场线的运动可以被视为“珠上导线”近似。如果考虑重力和离心力，这样的运动具有平衡点，其中一些是稳定的。在大多数情况下，大约百分之几的可能位置都可能保持稳定。相应的振荡频率跨越自旋频率的从零到 $\sqrt{3}$ 的范围。我们认为，这种变异模式可能在爆发期间在某些 X 射线脉冲星中被激发，并在功率密度谱中的断裂频率附近产生峰值宽带噪声分量，并在其中产生一些准周期振荡特征。这个频率范围。