On Testing the Kerr Metric of the Massive Black Hole in the Galactic Center via Stellar Orbital Motion: Full General Relativistic Treatment

Understand

The S-stars in the Galactic center (GC) are anticipated to provide unique dynamical constraint on the spin of the GC massive black hole (MBH).

• In this paper, we develop a fast full general relativistic method to simultaneously constrain the MBH mass, spin, and spin direction by considering both the motion of a star and the propagation of photons from the star to a distant observer.
• Assuming some example stars, we demonstrate that the spin-induced effects on the projected trajectory and redshift curve of a star depend on both the value and the direction of the spin.
• The maximum effects over a full orbit can differ by a factor upto more than one order of magnitude for cases with significantly different spin directions.