paper

A Possible Origin of kHZ QPOs in Low-Mass X-ray Binaries

arXiv:2002.10630 · doi:10.1093/pasj/psaa019

Abstract

A possible origin of kHz QPOs in low-mass X-ray binaries is proposed. Recent numerical MHD simulations of accretion disks with turbulent magnetic fields of MRI definitely show the presence of two-armed spiral structure in quasi-steady state of accretion disks. In such deformed disks, two-armed ( $m = 2$ ) c-mode ( $n = 1$ ) oscillations are excited by wave-wave resonant instability. Among these excited oscillations, the fundamental in the radial direction ( $n_{r} = 0$ ) will be the higher kHz QPO of a twin QPOs, and the first overtone ( $n_{r} = 1$ ) in the radial direction will be the lower kHz QPO of the twin. A possible cause of the twin high-frequency QPOs (HFQPOs) in BH X-ray binaries is also discussed.

20 pages, 6 figures; To be published in Publ. Aston. Soc. Japan, Vol. 72 (2020)