_{rot}≍580 Hz (or alternatively f

_{rot}≍290 Hz) of the neutron star in 4U 1636-53. It is shown that only two variants of the RS model based on the Kerr approximation are compatible with two EoS applied in the Hartle-Thorne theory for f

_{rot}≍580 Hz, while no variant of the RS model is compatible for f

_{rot}≍290 Hz. The two compatible variants of the RS model are those giving the best fits of the observational data. However, a self-consistency test by fitting the observational data to the RS model with oscillation frequencies governed by the Hartle-Thorne geometry described by three spacetime parameters M,a and (quadrupole moment) q related by the two available EoS puts strong restrictions. The test admits only one variant of the RS model of twin HF QPOs for the Hartle-Thorne theory with the EoS predicting the parameters of the neutron star M≍2.10 M

_{☉}, a≍0.208, and q/a

^{2}≍1.77.

Read More