Galaxy clusters, often likened to the large urban centers of the universe, house numerous giant elliptical galaxies that have reached their growth limits and ceased star formation. The reason behind the halt in star formation remains an enigma. In a recent study, scientists used the James Webb Space Telescope to explore a protocluster, which acts as a precursor to current galaxy clusters, shedding light on how supermassive black holes can inhibit star formation, leading to the development of giant elliptical galaxies.
The process of galaxy formation and the completion of their growth is a crucial topic in astrophysics. Galaxy clusters, dense regions in the universe, are primarily made up of giant elliptical galaxies—these are substantial, ancient structures that contain predominantly old stars. While the exact reasons for the cessation of star formation in these galaxies is still under discussion, one prevalent theory suggests that supermassive black holes (SMBHs) might significantly contribute to this phenomenon. Their powerful energy could reduce gas supply to galaxies, which might facilitate the emergence of today’s giant elliptical galaxies.
In this context, a collaborative team of researchers examined massive galaxies within an ancient cluster named the Spiderweb protocluster, located 11 billion light years away, utilizing data from the James Webb Space Telescope (JWST). The study was spearheaded by Associate Professor Rhythm Shimakawa from Waseda University in Japan, along with Dr. Yusei Koyama from the National Astronomical Observatory of Japan, Prof. Tadayuki Kodama from Tohoku University, and other notable scientists such as Dr. Helmut Dannerbauer and Dr. J. M. Perez-Martinez from the Instituto de AstrofÃsica de Canarias and Universidad de La Laguna in Spain. Their research findings were published in the Monthly Notices of the Royal Astronomical Society: Letters on December 18, 2024.
By utilizing the Near-Infrared Camera on the JWST, the researchers successfully generated high-resolution maps of hydrogen recombination lines, which reflect star formation activity and signs of SMBH presence. Their detailed examination indicated that massive galaxies housing active SMBHs showed no indicators of ongoing star formation, suggesting that their growth is significantly restricted by these black holes. This outcome reinforces the theoretical assertion that the formation of giant elliptical galaxies is connected with past SMBH activity.
Dr. Shimakawa expressed his enthusiasm, stating, “Our team has been investigating the Spiderweb protocluster for over a decade with the Subaru Telescope and other instruments. With the latest JWST data, we can now address the questions surrounding galaxy formation that have been building over the years.” He further concluded, “This study represents a pivotal advancement in our quest to understand the intertwined evolution of SMBHs and galaxies in these cosmic megacities.”
