Astronomers have uncovered a quasar in the early Universe exhibiting unexpected growth patterns in its central black hole. This discovery, made by an international team led by researchers from Waseda University and Tohoku University, reveals a supermassive black hole accreting matter at a remarkable rate—approximately 13 times the theoretical “Eddington limit.” It also emits bright X-rays and launches a powerful radio jet, a combination that challenges existing astrophysical models.
The quasar, identified through data from the Subaru Telescope, showcases a unique blend of characteristics. It is not only consuming material at an extraordinary pace but also radiating intense X-rays and producing a strong radio jet. Observations suggest that such features were not expected to coexist, making this discovery particularly significant for understanding black hole growth in the Universe’s formative years.
Understanding Black Hole Growth
Supermassive black holes, which can have masses ranging from millions to billions of times that of the Sun, typically reside at the centers of galaxies. They grow by drawing in surrounding gas, which forms an accretion disk. As this material spirals inward, it generates a dense region of hot plasma, known as a corona, that emits X-rays. In certain instances, this process produces a narrow jet that is detectable at radio wavelengths. When actively consuming material, these black holes are classified as quasars.
A major question in astrophysics is how some of these supermassive black holes achieved such enormous sizes so early in cosmic history. One proposed explanation for this rapid growth is a phenomenon known as super-Eddington accretion. Under normal conditions, the radiation from infalling material exerts an outward pressure, limiting the growth of the black hole. However, certain extreme conditions may allow for short bursts of growth that exceed this limit.
To investigate this hypothesis, researchers employed the near-infrared spectrograph (MOIRCS) on the Subaru Telescope to analyze the gas motion around the quasar. Their analysis of the Mg II (2800 Å) emission line indicated that the black hole existed approximately 12 billion years ago and is accreting matter at a rate significantly above the Eddington limit, based on X-ray data.
Implications for Cosmic Evolution
What distinguishes this quasar is its behavior across various light wavelengths. Existing theoretical models suggest that, during super-Eddington growth, changes in the accretion flow’s inner structure should diminish X-ray emission and reduce jet activity. Contrary to these predictions, this quasar exhibits strong X-ray brightness and a powerful radio jet simultaneously.
The findings imply that the black hole is undergoing an extreme growth phase while still maintaining an actively emitting corona and jet. Researchers propose that the quasar may represent a brief transitional state, possibly following a sudden influx of gas. This surge in material could propel the black hole into a super-Eddington growth mode, during which both the X-ray corona and the radio jet remain highly energized before stabilizing into a more conventional growth pattern.
The powerful radio signals detected indicate that the jet has enough energy to influence its surroundings. Such jets can heat or disrupt gas within the host galaxy, potentially impacting star formation and shaping the evolution of galaxies alongside their central black holes. The relationship between super-Eddington growth and jet-driven feedback remains an area of active research, and this quasar serves as a crucial reference point for testing new theoretical models.
Lead author Sakiko Obuchi from Waseda University stated, “This discovery may bring us closer to understanding how supermassive black holes formed so quickly in the early Universe. We want to investigate what powers the unusually strong X-ray and radio emissions, and whether similar objects have been hiding in survey data.”
The findings were published in the Astrophysical Journal on January 21, 2026. The research was supported by Grants-in-Aid for Scientific Research and the JST FOREST Program, among other funding sources. The Subaru Telescope, operated by the National Astronomical Observatory of Japan, is recognized for its significant contributions to astronomical research, and the team acknowledges the cultural and natural importance of Maunakea in Hawai`i, the site of these observations.
This discovery not only deepens our understanding of black hole growth but also opens avenues for further exploration into the early stages of cosmic evolution.
