Astronomers identify Nāpōwawāʻenakaulua as the oldest known compact quasar pair
Astronomers have identified the most distant compact pair of quasars yet found, a duo of rapidly feeding supermassive black holes seen as they were just 900 million years after the Big Bang. The system, catalogued as J1602+4228AB and nicknamed Nāpōwawāʻenakaulua, is also the tightest quasar pair known from cosmic dawn, the early era of first stars and galaxies. According to the research team, current theory offers no firm explanation for how black holes this massive could have grown so quickly, let alone two of them side by side.
A rare pair in the early Universe
The discovery was led by Silvia Onorato, a postdoctoral research associate at NSF NOIRLab, and appears in The Astrophysical Journal Letters. It combines data from the James Webb Space Telescope (JWST) with follow-up from the Gemini North telescope on Maunakea, Hawaiʻi.
The two black holes are separated by about 18,100 light-years, roughly one-fifth the diameter of the Milky Way. Their masses are about 1.5 billion and 400 million times that of the Sun. Onorato noted that these values are comparable to the black holes seen in the present-day Universe, even though the system is observed when the cosmos was only about one-thirteenth of its current age.
A quasar is a supermassive black hole shining brightly because it is pulling in gas and stars, with part of the infalling mass converted to energy. Quasars can outshine every star in their host galaxy. Because galaxy interactions and mergers are common, astronomers expect close quasar pairs to be plentiful. They are hard to find, though. The quasar phase is relatively brief, the objects are faint at such distances, and at small separations the two members are difficult to resolve. Nāpōwawāʻenakaulua is only the third quasar pair known from cosmic dawn.
From JWST survey to Gemini confirmation
The pair emerged from the Aether survey, a JWST program led by Emanuele Paolo Farina of NSF NOIRLab/Gemini to build a census of early-Universe objects. Using JWST’s Near-Infrared Spectrograph Integral Field Unit, the survey gathered 200 quasars, about 43% of all those known at this stage of cosmic history. During visual inspection of the data, the team noticed that quasar J1602+4228A had a companion.
Gemini North’s Gemini Near-Infrared Spectrograph (GNIRS) then separated the two sources. The companion, J1602+4228B, is faint and lies very close to its neighbor, which should have made ground-based detection nearly impossible. Onorato said unusually clear, sharp skies over Maunakea let the team collect the data in just two nights.
The Gemini Multi-Object Spectrograph (GMOS) was used to test whether a foreground gravitational lens might be creating the fainter quasar’s apparent image. Differences in the shapes of the two spectra led the team to favor a genuine physical pair. A lens model is still needed to rule out lensing definitively.
What it may reveal
The origin of the system remains unresolved. The researchers suggest it may mark an extreme peak in the matter density of the early Universe, where galaxy interactions drove star formation and rapid black hole growth at the same time. Onorato described it as a laboratory for studying how the first massive galaxies and their central black holes assembled through direct interactions.
The Hawaiian name
The nickname was created by Larry Kimura, a professor at Ka Haka ʻUla O Keʻelikōlani, the University of Hawaiʻi’s Hawaiian Language College, through the A Hua He Inoa program at the ʻImiloa Astronomy Center of Hawaiʻi. It combines Hawaiian terms for fathomless dark power, for the black holes, for the heat and brilliance of the accreting matter, and for a pair. It also echoes two earlier names from the program: Pōwehi, the first black hole image in 2019, and Pōniuāʻena, the most distant quasar known when it was found in 2020.
Gemini North is part of the International Gemini Observatory, which is operated by NSF NOIRLab and led by the U.S. National Science Foundation with partners Canada, Chile, Brazil, Argentina and the Republic of Korea.
Source: noirlab.edu
