A hidden intermediate-mass black hole could account for the three distinct populations of stars orbiting Sagittarius A*, the supermassive black hole at the Milky Way’s center. Researchers built a model showing how one tilted companion object can shape all three groups through gravitational effects. The work was detailed in a recent arXiv paper.
The model starts from the assumption that all stars near Sagittarius A* formed together in one disc. An object with several hundred to a thousand solar masses, orbiting on a steep tilt, then interacts with them.
Xiaochen Zheng of the Beijing Planetarium and colleagues showed that the object creates different outcomes for each population. Outer stars are stretched and tilted, sometimes reversing direction. A resonance effect keeps the clockwise disc relatively intact while the innermost S-stars are shaped mainly by their own interactions, producing the observed zone of avoidance.
Zheng said the single companion offers the simplest explanation, avoiding the need for multiple unrelated formation events. A candidate perturber is the IRS-13E star cluster, though further observations are required to confirm a central black hole.
Albert Zijlstra of the University of Manchester noted that finding such objects remains difficult and that previous candidates have not held up.