The Hubble Space Telescope has provided compelling evidence for an intermediate-mass black hole, estimated to be about 800 times the mass of the Sun, at the center of the globular star cluster Messier 4 (M4), located 6,000 light-years from Earth. Intermediate-mass black holes, typically ranging from 100 to 100,000 solar masses, have been elusive, existing between small black holes formed from collapsing stars and supermassive black holes found in galaxy centers. The research team, led by Eduardo Vitral, used over a decade of Hubble observations to track star movements around this suspected black hole, drawing circumstantial evidence from the gravitational influence on these stars.
Their findings suggest a concentrated mass that challenges alternative theories, such as the presence of multiple smaller black holes or stellar remnants. This central object in M4 exhibits a compactness that cannot be easily explained by current models. The study underscores Hubble’s unique capabilities in observing distant celestial objects and reinforces the potential existence of these rare intermediate-mass black holes, providing insights into their formation and the dynamics of globular clusters. The work has been published in the Monthly Notices of the Royal Astronomical Society.
