Correlated Frequency-Changes of Trapped Vertical p-mode Oscillations and kHz QPOs

Abstract

We have examined the frequencies of trapped two-armed ($m=2$) nearly vertical oscillations (vertical p-mode) in vertically isothermal disks with toroidal magnetic fields. The magnetic fields are stratified so that the Alfvén speed, $c_{\mathrm{A}}$, is constant in the vertical direction. We have particularly focused our attention on how frequencies of the fundamental mode ($n_{\mathrm{r}}=0$) and first overtone ($n_{\mathrm{r}}=1$) in the radial direction change with correlation, when the ratio $c_{\mathrm{A}}^2/c_{\mathrm{s}}^2$ changes, $c_{\mathrm{s}}$ being the isothermal acoustic speed. The results show that in the case where the oscillations are fundamental mode ($n=1$) in the vertical direction, the correlated frequency changes of the above-mentioned oscillations seem to well describe, with standard values of the mass and spin of the central sources, the frequency correlation of kHz QPOs observed in neutron-star X-ray binaries.

11 pages, 4 figures, accepted in PASJ 63, No. 5 (Oct, 2011)

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Cited by in corpus (6)

• An Attempt to Describe Frequency Correlations among kHz QPOs and HBOs by Two-Armed Nearly Vertical Oscillations
• Dynamics of the Innermost Accretion Flows Around Compact Objects: Magnetosphere-Disc Interface, Global Oscillations and Instabilities
• A Resonantly-Excited Disk-Oscillation Model of High-Frequency QPOs of Microquasars
• An Attempt to Describe Frequency-Correlations among kHz QPOs and HBOs by Two-Armed Vertical p-mode Oscillations: Case of No Magnetic Field
• A Possible Origin of kHZ QPOs in Low-Mass X-ray Binaries
• Trapped, Two-Armed, Nearly Vertical Oscillations in Disks with Toroidal Magnetic Fields II: Effects of Finite Thickness