Context :

Aims : Frequencies of the three quasi-periodic oscillation ( QPO ) modes observed simultaneously in the accreting black hole GRO J1655-40 are compared with the predictions of models .
Models in which all three QPO signals are produced at the same radius are considered : these include different versions of relativistic precession , epicyclic resonance , tidal disruption , and warped disc models .
Models that were originally proposed to interpret only the twin high-frequency QPOs are generalized here to interpret also the low-frequency QPO in terms of relativistic nodal precession .
Inferred values of the black hole mass and spin from each QPO model are compared with the mass measured from optical observations and the spin inferred from X-ray spectroscopy techniques .
We find that along with the relativistic precession model predicting M = ( 5.3 \pm 0.1 ) \leavevmode \nobreak M _ { \odot } ,a = 0.286 \pm 0.004 , the so-called total precession model ( M = ( 5.5 \pm 0.1 ) \leavevmode \nobreak M _ { \odot } ,a = 0.276 \pm 0.003 ) , and the resonance epicyclic model with beat frequency ( M = ( 5.1 \pm 0.1 ) \leavevmode \nobreak M _ { \odot } ,a = 0.274 \pm 0.003 ) also satisfy the optical mass test .
We compare our results with those inferred from X-ray spectral measurements .

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