A possible explanation of the parallel tracks in kilohertz quasi-periodic oscillations from low-mass X-ray binaries

作者：Shi, Chang-Sheng^*; Zhang, Shuang-Nan; Li, Xiang-Dong

来源：Monthly Notices of the Royal Astronomical Society, 2018, 479(4): 5049-5059.

DOI：10.1093/mnras/sty1191

• accretion: accretion discs
• MHD
• stars: magnetic fields
• X-rays: binaries

We recalculate the modes of the magnetohydrodynamics (MHD) waves in the MHD model of the kilohertz quasi-periodic oscillations (kHz QPOs) in neutron star low-mass X-ray binaries (NS-LMXBs), in which the compressed magnetosphere is considered. A method on point-by-point scanning for every parameter of a normal LMXBs is proposed to determine the wavenumber in an NS-LMXB. Then dependence of the twin kHz QPO frequencies on accretion rates (<(M) over dot>) is obtained with the wavenumber and magnetic field (B-*) determined by our method. Based on the MHD model, a new explanation of the parallel tracks, i.e. the slowly varying effective magnetic field leads to the shift of parallel tracks in a source, is presented. In this study, we obtain a simple power-law relation between the kHz QPO frequencies and in those sources. Finally, we study the dependence of kHz quasi-periodic oscillation frequencies on the spin, mass, and radius of a neutron star. We find that the effective magnetic field, the spin, mass, and radius of a neutron star lead to the parallel tracks in different sources.

• 出版日期2018-10
• 单位南京大学; 中国科学院; 海南大学; 中国科学院国家天文台; 中国科学院大学