Jing Wang, H. K. Chang, Cheng-min Zhang, D. H. Wang, L. Chen
Using the recently published data of twin kHz quasi-period oscillations
(QPOs) in neutron star low-mass X-ray binaries (LMXBs), we study the different
profiles between bright Z sources and less luminous Atoll sources in a
statistical way. We find the quality factors of upper kHz QPOs show a narrow
distribution both for Z sources and Atoll sources, which concentrate at 7.98
and 9.75 respectively, the quality factors of lower kHz QPOs show a narrow
distribution for Z sources and a broader distribution for Atoll sources, which
concentrate at 5.25 and 86.22 respectively. In order to investigate the
relation between the quality factor and the peakfrequency of kHz QPOs, we fit
the data with power-law, linear and exponential functions, respectively. There
is an obvious trend that the quality factors increase with the peak frequencies
both for upper and lower QPOs. The implications of our results are discussed.
View original:
http://arxiv.org/abs/1101.0655
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