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arXiv 2005.13508astro-ph.HE
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作为X射线谱仪带限噪声源的倾斜偶极磁层的惯性振荡模式

Inertial oscillation modes of an inclined dipolar magnetosphere as a source of band-limited noise in X-ray pulsars

Pavel Abolmasov, Anton Biryukov

摘要:

强磁化恒星的磁场会因冻结状态而捕获导电物质。在无力状态下,物质沿着场线的运动可以用“线上的珠子”近似来考虑。如果考虑重力和离心力,这样的运动有平衡点,其中一些是稳定的。在大多数情况下,在大约百分之几的可能地点中,稳定是可能的。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,在某些X射线爆发过程中,这种变化模式可能被激发,并在功率密度谱中产生在突变频率附近的峰值宽带噪声分量,以及在该频率范围内产生某些准周期振荡特征。这种变化的存在并不需要质量吸积率的任何变化,只涉及少量的物质渗透从磁盘和磁流由于交换不稳定性。

英文摘要:

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.

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