6 HZ QUASI-PERIODIC OSCILLATIONS FROM LOW-MASS X-RAY BINARIES - THE SOUND OF AN ACCRETION DISK

Date

1992-04-01

Author

ALPAR, MA
HASINGER, G
SHAHAM, J
YANCOPOULOS, S

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Quasiperiodic oscillations (QPOs) at frequencies of 5-8 Hz are a common feature of low-mass X-ray binaries (LMXBs) during their normal branch (NB) spectral states. We propose that this frequency band is essentially a band of rotation frequencies in a thick accretion disk. The high luminosities in the NB state give rise to the thick disk and slow down the dynamical timescales. Density and optical-thickness perturbations in a subsonic region of the disk have the frequency spectrum of sound in a rotating medium. X-rays scattered through the subsonic region are modulated by long wavelength optical-thickness oscillations whose frequencies, determined by the rotation rate and vorticity, are observed as the NB QPOs.

Subject Keywords

Accretion disks, X-Ray binaries, Quasi-periodic oscillations, Sound

URI

https://hdl.handle.net/11511/67411

Collections

Department of Physics, Article