Recent observations from the James Webb Space Telescope (JWST) have provided the first significant evidence supporting the existence of “monster stars” in the early Universe. These colossal stars, potentially weighing between 1,000 and 10,000 solar masses, could explain the formation of supermassive black holes (SMBHs) less than one billion years after the Big Bang. This discovery could reshape our understanding of cosmological evolution during the Universe’s formative years.
For over two decades, astronomers have grappled with how supermassive black holes could emerge so soon after the Big Bang, as conventional models suggest there was insufficient time for their formation through traditional processes of black hole creation and mergers. The recent findings challenge these models and lend credence to an alternative hypothesis. This theory posits that the seeds of SMBHs formed from collapsing clouds of cosmic gas, known as direct collapse black holes (DCBHs). Alternatively, it suggests that massive stars from the early Universe, referred to as Population III stars, could have left behind massive black holes.
The research team, led by Devesh Nandal, a Postdoctoral Fellow with the Swiss National Science Foundation from the University of Virginia and the Institute for Theory and Computation (ITC) at the Harvard & Smithsonian Center for Astrophysics, included notable experts such as Daniel Whalen, a Senior Lecturer in Cosmology at the University of Portsmouth, and Muhammad A. Latif, an astrophysicist from United Arab Emirates University. Their collaboration has yielded groundbreaking results.
Utilizing the JWST, the team examined a galaxy known as GS 3073, which was initially identified in 2022 by a separate group including Latif and Whalen. This galaxy exhibited an extreme nitrogen-to-oxygen ratio of 0.46, significantly higher than what would be expected from any known stellar types or explosions. This anomaly led the researchers to theorize that the first stars in the Universe, formed from turbulent flows of cold gas shortly after the Big Bang, contributed to this unusual chemical signature.
At the core of GS 3073 lies an actively feeding black hole, which may be the remnant of one of these “monster stars.” Such stellar objects could clarify why the JWST has detected multiple quasars that existed less than one billion years after the Big Bang. These quasars, also known as Active Galactic Nuclei (AGNs), are powered by SMBHs that accelerate surrounding gas and dust to near-light speeds, resulting in immense energy output that temporarily outshines all other stars in the galaxy.
Nandal stated in a University of Portsmouth press release that the team developed models illustrating how stars of this mass range evolve and the specific chemicals they produce. This modeling revealed that the nitrogen-to-oxygen ratio observed in GS 3073 can be explained by a process in which monster stars fuse helium in their cores to create carbon. This carbon then combines with hydrogen in the outer shell of the star to form nitrogen, which is subsequently distributed through convection currents and eventually released into space.
The implications of this research extend beyond the individual galaxy. The team’s models suggest that these monster stars do not explode as supernovae at the end of their life cycles. Instead, they collapse directly into massive black holes, serving as the “seeds” for the SMBHs observed today. Moreover, the nitrogen signature identified does not appear in stars that fall outside this specific mass range, reinforcing the uniqueness of these early stellar objects.
If confirmed, the existence of these monster stars could resolve two significant mysteries emerging from previous JWST observations. Additionally, these findings provide valuable insights into the Universe during the “Cosmic Dark Ages,” a period spanning from approximately 380,000 to one billion years after the Big Bang. Until recently, this era was largely inaccessible to astronomers due to the faintness of light from this period, necessitating advanced infrared optics like those employed by the JWST.
The researchers anticipate that future surveys will uncover more galaxies exhibiting similar nitrogen excesses, allowing scientists to further investigate the potential existence of these extraordinary stars. Whalen emphasized the importance of this research in advancing our understanding of the early Universe and the formation of its most massive structures. As astronomers continue to unravel the mysteries of our cosmos, the findings from GS 3073 mark a significant step forward in comprehending the origins of supermassive black holes and their progenitor stars.
