Speaker
Description
This talk proposes using resonant structures around a Kerr black hole as a model agnostic means of quantifying departures from the Kerr Metric. Initial observational evidence that these structure exist around Sgr A* is presented.
When a black hole is immersed into an astrophysical environment, the KAM theorem predicts that the spacetime geodesic structure will exhibit non-smooth departures from Kerr metric in regions where orbital resonances occur. I quantify the locations of resonant orbits and associated characteristic timescales. A preliminary survey of the published observational results for Sgr A reveals that all the statistical ’pacemaker’ frequencies identified by Leibowitz in X-ray and near-IR flaring activity can be associated with resonant structures if Sgr A has a dimensionless spin value near a ∼ 0.5.
Hotspots around Sgr A observed by the EHT and flares resolved by the GRAVITY experiment can be associated with region in which orbital resonances occur, providing an explanation for their origin as well as a mechanism rendering them stable.
It is thus proposed that some of the observed variability in the radiation emitted from Sgr A may result from interactions between inspiralling compact objects, the accretion disk and low order resonant structures found around the black hole. The Galactic speed trap and Galactic fish and release flare models are introduced as paradigms for discussing these interactions. We remark on the coincidence that the chronology of three flare dates recorded by the GRAVITY collaboration in 2018 nominally passes the Galactic Speed trap test. Noting that the dates at which the flares occur is consistent with timing of emission triggered by the resonant passage of a single intermediate mass ratio inspiralling object transiting a succession of resonant locations found in the regions to which polarization and astrometric data confine the emission.