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At least four high-frequency quasiperiodic oscillations (QPOs) at frequencies41Hz, 67Hz, 113Hz, and 167Hz were reported in a binary system GRS 1915+105hosting near-extreme Kerr black hole with a dimensionless spin a>0.98. We usethe idea of oscillations induced by the hump of the orbital velocity profile(related to locally non-rotating frames - LNRF) in discs orbiting near-extremeKerr black holes, which are characterized by a "humpy frequency" f_h, thatcould excite the radial and vertical epicyclic oscillations with frequenciesf_r, f_v. Due to non-linear resonant phenomena the combinational frequenciesare allowed as well. Assuming mass M=14.8M_sun and spin a=0.9998 for the GRS1915+105 Kerr black hole, the model predicts frequencies f_h=41Hz, f_r=67Hz,(f_h+f_r)=108Hz, (f_v-f_r)=170Hz corresponding quite well to the observed ones.For black-hole parameters being in good agreement with those givenobservationally, the forced resonant phenomena in non-linear oscillations,excited by the "hump-induced" oscillations in a Keplerian disc, can explainhigh-frequency QPOs in GRS 1915+105 within the range of observational errors.

astronomy and astrophysics

LNRF-velocity hump-induced oscillations of a Keplerian disc orbiting  near-extreme Kerr black hole: A possible explanation of high-frequency QPOs  in GRS 1915+105