Trapped, Two-Armed, Nearly Vertical Oscillations in Polytropic Disks

Abstract

We have examined trapping of two-armed nearly vertical oscillations in polytropic disks. Two-armed nearly vertical oscillations are interesting in the sense that they are trapped in an inner region of disks with proper frequencies, if the inner edge of disks is a boundary that reflects oscillations. The frequencies of the trapped oscillations cover the frequency range of kHz QPOs to low frequency QPOs in LMXBs, depending on the modes of oscillations. Low frequency trapped oscillations are particularly interesting since their trapped region is wide. These low frequency oscillations are, however, present only when $\Gamma (\equiv 1+1/N)$ is close to but smaller than 4/3 (when spin parameter $a_{\ast }$ is zero), where $N$ is the polytropic index. The above critical value 4/3 slightly increases as $a_{\ast }$ increases.

18 pages, 6 figures; To be published in PASJ 62 No.3 (2010)

References in corpus (4)

• On an excitation mechanism for trapped inertial waves in discs around black holes
• Excitation of Trapped Waves in Simulations of Tilted Black Hole Accretion Disks with Magnetorotational Turbulence
• Excitation of Trapped g-Mode Oscillations in Warped Disks around Black Holes
• Corotation Resonance and Diskoseismology Modes of Black Hole Accretion Disks

Cited by in corpus (5)

• An Attempt to Describe Frequency Correlations among kHz QPOs and HBOs by Two-Armed Nearly Vertical Oscillations
• Trapped, Two-Armed, Nearly Vertical Oscillations in Disks with Toroidal Magnetic Fields
• An Attempt to Describe Frequency-Correlations among kHz QPOs and HBOs by Two-Armed Vertical p-mode Oscillations: Case of No Magnetic Field
• Trapped, Two-Armed, Nearly Vertical Oscillations in Disks with Toroidal Magnetic Fields II: Effects of Finite Thickness
• Correlated Frequency-Changes of Trapped Vertical p-mode Oscillations and kHz QPOs