Fast-moving stars around an intermediate-mass black hole in ω Centauri

Area of Science:

• Astronomy and Astrophysics
• Black Hole Physics
• Stellar Dynamics

Background:

• Black holes span a wide mass range, from stellar remnants (5-150 solar masses) to supermassive ones (>10^5 solar masses).
• A gap exists for intermediate-mass black holes (IMBHs) between 150 and 10^5 solar masses, crucial for understanding supermassive black hole origins.
• Previous claims of a central black hole in Omega Centauri were debated due to potential stellar mass black hole contributions and lack of conclusive evidence.

Purpose of the Study:

• To investigate the presence and mass of a potential intermediate-mass black hole in the globular cluster Omega Centauri.
• To resolve discrepancies in previous studies by seeking direct evidence of a central massive object.
• To contribute to the understanding of supermassive black hole formation mechanisms in the early universe.

Main Methods:

• Observation of seven fast-moving stars within the central 0.08 parsecs of Omega Centauri.
• Analysis of stellar velocities to determine if they exceed the cluster's expected central escape velocity.
• Modeling the gravitational influence required to explain the observed high velocities of these stars.

Main Results:

• Detection of seven stars with velocities significantly higher than the predicted escape velocity for Omega Centauri's core.
• These high velocities indicate the stars are gravitationally bound to a massive central object.
• A firm lower limit for the central black hole's mass is established at approximately 8,200 solar masses.

Conclusions:

• The findings provide strong evidence for an intermediate-mass black hole at the center of Omega Centauri.
• This discovery offers a significant candidate for an IMBH in the local universe.
• The existence of such IMBHs supports theories on the formation pathways of supermassive black holes.