A star cluster close to the supermassive black hole Sagittarius A* (SgrA*) at the center of our galaxy has shown signs of a potential intermediate-mass black hole, according to an international research team under the direction of PD Dr. Florian Peißker. A study detailed this discovery and published it in The Astrophysical Journal. Intermediate-mass black holes are rare cosmic objects believed to have formed shortly after the Big Bang and could play a key role in the development of supermassive black holes.

The star cluster, known as IRS 13, is located just 0.1 light years from SgrA*. Although this distance is relatively close in astronomical terms, it still equates to a journey of about twenty times across our solar system. Researchers observed that the stars in IRS 13 move in an unusually orderly fashion, contrary to the expected random arrangement. Two possibilities emerge from this regular movement: either SgrA* influences the stars or an unseen object is influencing their arrangement.

Recent observations using the Very Large Telescope, the Atacama Large Millimeter Array (ALMA), and the Chandra X-ray Observatory telescopes revealed that the cluster’s compact shape could be due to an intermediate-mass black hole at its center. The team detected X-rays and ionized gas rotating at high speeds around the suspected black hole, reinforcing this theory. Additionally, IRS 13’s high star density surpasses that of any other known star cluster in the Milky Way, further supporting the existence of an intermediate-mass black hole.

This possible black hole discovery could provide crucial insights into the growth of supermassive black holes like SgrA*. Planned future observations with the James Webb Space Telescope (JWST) and the Extremely Large Telescope (ELT), currently under construction, aim to explore the star cluster’s dynamics in more detail and confirm the presence of the black hole. This ongoing research promises to enhance our understanding of cosmic structures and their formation.

References

• University of Cologne. (2024, July 18). Another intermediate-mass black hole discovery at the center of our galaxy. Phys.Org; University of Cologne. https://phys.org/news/2024-07-intermediate-mass-black-hole-discovery.html
• Peißker, F., Zajaček, M., Labaj, M., Thomkins, L., Elbe, A., Eckart, A., Labadie, L., Karas, V., Sabha, N. B., Steiniger, L., & Melamed, M. (2024). The Evaporating Massive Embedded Stellar Cluster IRS 13 Close to Sgr A*. II. Kinematic Structure. The Astrophysical Journal, 970(1), 74. https://doi.org/10.3847/1538-4357/ad4098
• Peißker, F., Zajaček, M., Thomkins, L., Eckart, A., Labadie, L., Karas, V., Sabha, N. B., Steiniger, L., & Melamed, M. (2023). The Evaporating Massive Embedded Stellar Cluster IRS 13 Close to Sgr A*. I. Detection of a Rich Population of Dusty Objects in the IRS 13 Cluster. The Astrophysical Journal, 956(2), 70. https://doi.org/10.3847/1538-4357/acf6b5