TESTING THE TWIN kHz QPO MODELS OF NEUTRON STAR

Abstract

We take the data of twin kilohertz quasi-periodic oscillations (kHz QPOs) in neutron stars (NSs) published before 2011 as the samples, which include 15 Atoll sources and 8 Z sources. Then we test the correlation between the twin peak kHz QPOs, and compare with the samples. We find the power law relation between the lower-frequency (ν1) and the upper-frequency (ν2) of kHz QPOs can fit the data much better than the other models. For the Atoll (Z) sources, the best fitting coefficient and index of power law are a = 687 (720) and b =1.50 (1.83) respectively. The Chi-square per degree of freedom (χ2/d.o.f.) are 1.93 and 1.49 respectively.