Quasiperiodic oscillations and Tomimatsu-Sato {\delta} = 2 space-time
  We model the spacetime of low-mass X-ray binaries with the Tomimatsu-Sato {\delta} = 2 (TS2) metric and study the properties of the orbital and the epicyclic frequencies. The numerical analysis shows that the properties of the characteristic frequencies of oscillation do not differ qualitatively from those of the Kerr black hole. Estimates for the angular momenta of the three stellar mass black hole candidates GRO 1655-40, XTE 1550-564 and GRS 1915+105 are made with the application of the nonlinear resonance model. We find agreement between the predictions based on the 3 : 2 nonlinear resonance model for a TS2 background and the current estimates found in the literature. 
Ivan Zh. Stefanov, Galin G. Gyulchev, Stoytcho S. Yazadjiev
astro-ph.HE gr-qc