Evidence for GR rotational frame-dragging in the light from the Sgr A* supermassive black hole

Abstract

The analysis of flare start-times confirms the periods found years ago (Aschenbach et al., 2004) in the near-infrared and X-ray light-curves related to the Sgr A* black hole. The assignment of the frequencies found to radial and vertical epicyclic frequencies $\nu\sb{\rm r}$, $\nu\sb{\rm v}$, respectively, as well as to the Kepler orbital frequency $\nu\sb{\rm K}$ reveals resonances of $\nu\sb{\rm v}$ / $\nu\sb{\rm r}$=7:2, and $\nu\sb{\rm K}$ / $\nu\sb{\rm v}$=3:1. The highest observed frequency of 10 mHz is identified as the Kepler frequency corrected by the rotational frame-dragging frequency, as expected from the Lense-Thirring effect. These frequency assignments conclude a black hole mass of M = (4.10-4.34)$\times10\sp{6} M_\odot$ and a spin of a = (0.99473-0.99561).