Astronomers, leveraging the power of the James Webb Space Telescope (JWST), have discovered the most ancient pair of supermassive black-hole-powered quasars ever observed. This groundbreaking find, however, presents a significant puzzle: according to current theoretical models, these quasars should not have existed so early in the universe’s history.
Nāpōwawāʻenakaulua: A Cosmic Anomaly
The closely spaced quasar pair, confirmed using the Gemini North telescope, is designated J1602+4228AB and nicknamed Nāpōwawāʻenakaulua. This Hawaiian name translates to “two celestial bodies in the endless powerful darkness that are reborn in heat and inject energy into the universe.” These quasars were observed as they appeared approximately 900 million years after the Big Bang, a time when the universe was in its nascent stages.
The challenge lies in the immense mass of the supermassive black holes powering these quasars. Existing theories suggest that black holes would not have had sufficient time to grow to such extraordinary sizes so early in cosmic history. Nāpōwawāʻenakaulua is not only the most ancient and distant quasar binary system discovered to date, but the two supermassive black holes are also separated by a mere 18,100 light-years, roughly one-fifth the diameter of our Milky Way galaxy.
With individual masses estimated at 1.5 billion and 400 million times that of our Sun, Nāpōwawāʻenakaulua represents the closest known quasar pair from the cosmic dawn era – the period when the first stars, galaxies, and black holes began to emerge.
Explaining Early Supermassive Black Hole Growth
Quasars are among the most luminous objects in the universe. They form when supermassive black holes at the centers of massive galaxies are surrounded by a swirling disk of gas and dust, known as an accretion disk. The black hole continuously consumes matter from this disk.
The intense gravitational pull of the black hole causes the material in the accretion disk to orbit at high speeds, generating friction and emitting vast amounts of heat. This process results in the accretion disk radiating intensely, often outshining all the stars in its host galaxy combined. The bright light observed by astronomers is the quasar itself.
While finding quasars within the universe’s 13.8 billion-year history isn’t entirely surprising, discovering two so close together is exceedingly rare. Theoretically, such binary systems should be common, as galactic mergers frequently bring their central supermassive black holes into close proximity, potentially creating numerous quasar binaries separated by less than a typical galaxy’s size.
Challenges in Detection
However, astronomers face three major hurdles in their search for these systems:
- Supermassive black holes are only in their active quasar phase for a relatively short period in cosmic timescales.
- Even if two quasars are close, their extreme distance makes them appear very faint and difficult to detect from Earth.
- When supermassive black holes are both very close and extremely distant, distinguishing them as separate entities with telescopes is exceptionally challenging.
Despite these difficulties, astronomers have managed to find quasar binaries. Some of these discoveries, both in terms of their timing and separation, have already begun to challenge existing theories of black hole growth.
The Nāpōwawāʻenakaulua Enigma
The period less than a billion years after the universe’s birth is particularly problematic. Current models suggest that black holes require at least a billion years to accumulate enough matter and merge to reach masses of millions or even billions of times that of the Sun.
Since its operational start in 2022, the Webb telescope has repeatedly detected quasars powered by supermassive black holes that appeared only about 400 million years after the Big Bang. If these earlier discoveries have already strained existing theories, Nāpōwawāʻenakaulua could further shake current models. This is the third quasar binary discovered by astronomers in the cosmic dawn era.
The research team identified this pair within data from the Webb telescope’s Aether survey project, which systematically surveys celestial objects in the early universe. Using Webb’s Near-Infrared Spectrograph (NIRSpec) Integral Field Unit, researchers have already identified around 200 quasars, nearly half the total number of known early-universe quasars.
While reviewing the Aether project’s data, researchers found that the quasar designated J1602+4228A was not alone; it had a companion, J1602+4228B. Distinguishing these two quasars from ground-based telescopes would have been nearly impossible. However, the Gemini North telescope successfully accomplished this task, thanks to precise timing and exceptionally clear weather conditions atop Maunakea in Hawaii, the dormant volcano where the telescope is located.
“We currently lack a clear theoretical explanation for why such a massive quasar would exist so early in the universe, let alone two of them,” stated Silvia Onorato, the lead researcher from the National Science Foundation’s National Optical-Infrared Astronomy Research Laboratory (NOIRLab). “When we observed Nāpōwawāʻenakaulua, the universe was less than one-thirteenth of its current age. It’s astonishing that these two supermassive black holes already possessed masses comparable to those we observe today.”
While the formation mechanism of Nāpōwawāʻenakaulua remains a mystery, it could offer invaluable insights into how galaxies in the cosmic dawn period gradually assembled, merged, and how early cosmic structures took shape – a crucial phase in the universe’s evolutionary journey.
Onorato added, “Nāpōwawāʻenakaulua represents a very unique environment. It provides astronomers with a natural laboratory to study how the first massive galaxies and their central black holes assembled through direct interactions between galaxies in the early universe.”
The team published their findings on November 10th in The Astrophysical Journal Letters.
