The correlations between the spin frequencies and kHz QPOs of Neutron Stars in LMXBs

Abstract

We studied the correlations between spin frequencies and kilohertz quasi-periodic oscillations (kHz QPOs) in neutron star low mass X-ray binaries. The updated data of kHz QPOs and spin frequencies are statistically analyzed. We found that when two simultaneous kHz QPOs are present in the power spectrum, the minimum frequency of upper kHz QPO is at least 1.3 times larger than the spin frequency, i.e. ν_{s}<ν_{2min}/1.3. We also found that the average kHz QPO peak separation in 6 Atoll sources anti-correlates with the spin frequency in the form \lan\dn\ran = -(0.19\pm0.05)\ns+(389.40\pm21.67)Hz. If we shifted this correlation in the direction of the peak separation by a factor of 1.5, this correlation matches the data points of the two accretion powered millisecond X-ray pulsars, SAX J1808.4-3658 and XTE J1807-294.

4 pages, 2 figures, accepted for publication in A&A

References in corpus (2)

• Evidence for 1122 Hz X-Ray Burst Oscillations from the Neutron-Star X-Ray Transient XTE J1739-285
• Timing Features of the Accretion--driven Millisecond X-Ray Pulsar XTE J1807--294 in 2003 March Outburst

Cited by in corpus (8)

• Detecting gravitational wave emission from the known accreting neutron stars
• Is there a link between the neutron-star spin and the frequency of the kilohertz quasi-periodic oscillations?
• Discovery of the upper kilo-Hz QPO from the X-ray transient Aql X-1
• Wave Excitation in Disks Around Rotating Magnetic Stars
• Gravitational waves from rapidly rotating neutron stars
• Rotational parameters of strange stars in comparison with neutron stars
• Fe K$\alpha$ and Fe K$\beta$ line detection in the NuSTAR spectrum of the ultra-bright Z-source Scorpius X-1
• A new correlation with lower kilohertz quasi-periodic oscillation frequency in the ensemble of low-mass X-ray binaries