Supermassive black holes, some containing billions of times the mass of the Sun, lie at the center of most galaxies, and researchers continue to observe them even in the early universe. The existence of these giants just a few billion years after the Big Bang poses a profound mystery: How did they grow so massive so quickly? Observing such rapid growth challenges current models of black hole formation, which typically predict a much slower accumulation of mass.
A new discovery has shed light on this puzzle. Astronomers recently detected a low-mass supermassive black hole, named LID-568, that is devouring material at an extraordinary rate — about 1.5 billion years after the Big Bang. This discovery provides valuable insights into how supermassive black holes may have rapidly grown during the universe’s earliest epochs. The team, led by Hyewon Suh from the International Gemini Observatory and NSF’s NOIRLab, used the James Webb Space Telescope (JWST) to examine a sample of galaxies from the COSMOS Legacy survey, conducted by the Chandra X-ray Observatory. These galaxies emit intense X-rays, yet remain almost invisible in the optical and near-infrared spectrums, making them challenging to study with conventional telescopes.
The unique capabilities of JWST allowed astronomers to examine these faint signals in the infrared, unveiling details of LID-568 that other telescopes could not observe. Within this group of galaxies, LID-568 stood out due to its intense X-ray emissions, suggesting extreme activity around its central black hole. However, pinpointing its exact location within the field of view was challenging, raising concerns about centering it accurately. To overcome this, the team used an innovative approach with JWST’s Near Infrared Spectrograph (NIRSpec) instrument. Unlike traditional slit spectroscopy, which captures light from a narrow slice, NIRSpec’s integral field spectrograph provides a spectrum for each pixel, delivering a comprehensive view of both the black hole and its surrounding region.
Thanks to NIRSpec, the team identified not only LID-568’s precise location but also observed energetic outflows of gas around it. The speed and scale of these outflows suggest that a substantial part of the black hole’s mass may have accumulated in a single, intense phase of accretion. Observing this rapid inflow and outflow process led the researchers to conclude that LID-568’s growth likely occurred in a burst rather than gradually. Emanuele Farina, another member of Suh’s team, noted that JWST’s sensitivity and innovative approach were essential for capturing this faint but highly informative target.
The discovery of LID-568 yielded an unexpected revelation: it is devouring material at a rate exceeding 40 times the theoretical Eddington limit. The Eddington limit describes the balance between the outward pressure of radiation and the inward pull of gravity in a black hole. Beyond this limit, the radiation pressure should theoretically push back against further matter intake, creating an equilibrium. However, LID-568 is consuming material at such a high rate that it defies this limit, showing luminosity levels far above what should be possible under normal conditions.
Such extreme accretion rates indicate that certain black holes may find ways to exceed their natural feeding constraints, a phenomenon rarely observed but critical to understanding black hole growth in the universe’s early history. Julia Scharwächter, a co-author of the study, remarked that LID-568 is undergoing a “feast,” illustrating how a supermassive black hole’s mass can increase at an extraordinary pace under certain conditions. This discovery suggests that super-Eddington accretion may play a role in explaining how massive black holes could appear so soon after the Big Bang.
Understanding LID-568’s rapid feeding process could help astronomers refine their theories about black hole origins. Current theories propose that supermassive black holes form from “seeds” — either from the remnants of massive early stars (light seeds) or from the direct collapse of primordial gas clouds (heavy seeds). Observing LID-568’s super-Eddington accretion phase supports the idea that even small black hole seeds could grow swiftly through rapid feeding, regardless of their origin.
Furthermore, the team noted that the powerful outflows of gas observed around LID-568 might act as a form of regulation. These outflows could provide a release valve for the excess energy generated by such rapid accretion, preventing the system from becoming too unstable. The team plans follow-up observations with JWST to understand these mechanisms better and to investigate how this balance allows black holes to exceed their expected growth rates. Studying this balance of forces could answer long-standing questions about black hole evolution, shedding light on the extreme environments where supermassive black holes thrived in the early universe.
The research has been published in Nature Astronomy.
Source: Association of Universities for Research in Astronomy