Campana S
Astrophys J. 2000 May 1;534(1):L79-L82. doi: 10.1086/312634.
Starting from the observation that kilohertz quasi-periodic oscillations (kHz QPOs) occur in a very narrow range of X-ray luminosities in neutron star low-mass X-ray binaries, we try to link the kHz QPO observability to variations of the neutron star magnetospheric radius, in response to changing mass inflow rate. At low luminosities, the drop-off of kHz QPO activity may be explained by the onset of the centrifugal barrier, when the magnetospheric radius reaches the corotation radius. At the opposite side, at higher luminosities, the magnetospheric radius may reach the neutron star and the vanishing of the magnetosphere may lead to the stopping of the kHz QPO activity. If we apply these constraints, the magnetic fields of atoll [B approximately 0.3-1x108 G for Aql X-1] and Z [B approximately 1-8x108 G for Cyg X-2] sources can be derived. These limits naturally apply in the framework of beat-frequency models but can also work in the case of general relativistic models.
从中子星低质量X射线双星中千赫兹准周期振荡（kHz QPOs）出现在非常窄的X射线光度范围内这一观测结果出发，我们试图将kHz QPO的可观测性与中子星磁层半径的变化联系起来，以响应质量流入率的变化。在低光度下，当磁层半径达到共转半径时，离心屏障的出现可能解释了kHz QPO活动的下降。在相反的情况下，在高光度下，磁层半径可能到达中子星，磁层的消失可能导致kHz QPO活动停止。如果我们应用这些限制条件，就可以推导出环礁源[Aql X-1的B约为0.3 - 1×10^8 G]和Z源[Cyg X-2的B约为1 - 8×10^8 G]的磁场。这些限制自然适用于拍频模型的框架，但在广义相对论模型的情况下也适用。
