Black hole spin inferred from 3:2 epicyclic resonance model of high-frequency quasi-periodic oscillations

Understand

Estimations of black hole spin in the three Galactic microquasars GRS 1915+105, GRO J1655-40, and XTE J1550-564 have been carried out based on spectral and timing X-ray measurements and various theoretical concepts.

• Among others, a non-linear resonance between axisymmetric epicyclic oscillation modes of an accretion disc around a Kerr black hole has been considered as a model for the observed high-frequency quasi-periodic oscillations (HF QPOs).
• Estimates of spin predicted by this model have been derived based on the geodesic approximation of the accreted fluid motion.
• Here we assume accretion flow described by the model of a pressure-supported torus and carry out related corrections to the mass-spin estimates.