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

摘要: 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 timing X-ray measurements various theoretical concepts. Among others, a non-linear resonance between axisymmetric epicyclic oscillation modes an accretion disc around Kerr has considered as model for observed high-frequency quasi-periodic oscillations (HF QPOs). Estimates predicted by this derived geodesic approximation accreted fluid motion. Here we assume flow described pressure-supported torus carry related corrections to mass-spin estimates. We find that dimensionless 0.9, which case resonant eigenfrequencies rapidly decrease thickness increases. conclude assumed non-geodesic effects shift lower limit spin, implied independently measured masses, from a~0.7 a~0.6. Their consideration furthermore confirms compatibility with rapid 1915+105 provides highly testable predictions QPO frequencies. Individual sources moderate (a<0.9) should exhibit smaller spread 3:2 frequencies than near-extreme (a~1). This be further examined using large amount high-resolution data expected become available next generation instruments, such proposed Large Observatory Timing (LOFT).