Modified gravity leaves its fingerprint on stars near our galaxy's black hole

Using post-Newtonian equations, the authors simulated how S-stars near Sagittarius A* would move under MOG, a dark-matter-free alternative to general relativity. MOG measurably shifts orbital precession, and for large enough values of its free parameter, the deviations in position and velocity reach the threshold of current telescope precision. The catch: MOG's orbital signatures can closely mimic those of a dark matter halo, making clean interpretation tricky.