Investigation of the emission radii of kHz QPOs for the accreting millisecond X-Ray pulsars, Atoll and Z sources

Abstract

We infer the emission positions of twin kilohertz quasi-periodic oscillations (kHz QPOs) in neutron star low mass X-ray binaries (NS-LMXBs) based on the Alfven wave oscillation model (AWOM). For most sources, the emission radii of kHz QPOs cluster around a region of 16-19 km with the assumed NS radii of 15 km. Cir X-1 has the larger emission radii of 23-38 km than those of the other sources, which may be ascribed to its large magnetosphere-disk radius or strong NS surface magnetic field. SAX J1808.4-3658 is also a particular source with the relative large emission radii of kHz QPOs of 20 - 23 km, which may be due to its large inferred NS radius of 18 - 19 km. The emission radii of kHz QPOs for all the sources are larger than the NS radii, and the possible explanations of which are presented. The similarity of the emission radii of kHz QPOs (16-19 km) for both the low/high luminosity Atoll/Z sources is found, which indicates that both sources share the similar magnetosphere- disk radii.

8 pages, 4 figures

References in corpus (6)

• RXTE observations of the first transient Z source XTE J1701-462: shedding new light on mass accretion in luminous neutron star LMXBs
• Optical spectroscopy and photometry of SAX J1808.4-3658 in outburst
• X-ray time variability across the atoll source states of 4U 1636--53
• On the kHz QPO frequency correlations in bright neutron star X-ray binaries
• Discovery of the upper kilo-Hz QPO from the X-ray transient Aql X-1
• Timing Features of the Accretion--driven Millisecond X-Ray Pulsar XTE J1807--294 in 2003 March Outburst

Cited by in corpus (7)

• Timescale of twin-peak quasi-periodic oscillations and mass of accreting neutron stars
• Models of high-frequency quasi-periodic oscillations and black hole spin estimates in Galactic microquasars
• Constraining models of twin peak quasi-periodic oscillations with realistic neutron star equations of state
• Hard-tail emission in the soft state of low-mass X-ray binaries and their relation to the neutron star magnetic field
• The kHz QPOs as a probe of the X-ray color-color diagram and accretion-disk structure for the atoll source 4U 1728-34
• Probing the accretion disc structure by the twin kHz QPOs and spins of neutron stars in LMXBs
• Probing Black Hole Phase Transitions through Quasi-Periodic Oscillations