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Mass and Angular Momentum of Sgr A*

B. Aschenbach
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Abstract

For very fast spinning black holes with a>0.9953 the orbital velocity of a test particle unexpectly shows a positive radial gradient for low orbits, an effect of GR which has been overlooked so far. For a=0.99616 the maximum radial change of the orbital velocity equals the radial epicyclic frequency, which in turn is in a 1:3 resonance with the vertical epicyclic frequency. Application to Sgr A* using the quasi-periodic oscillations recently measured suggest that the mass of Sgr A* is 3.28 +/- 0.13 million solar masses.

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B. Aschenbach. 2004-10-13. Mass and Angular Momentum of Sgr A*. https://doi.org/10.1007/11403913_54

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