Closest quasar pair candidate at cosmic dawn deepens black-hole puzzle

Two quasars only 0.98 arcseconds apart, about 18,100 light-years in projection, shine from 900 million years after the Big Bang with black holes of roughly 1.5 billion and 400 million Suns, although the team cannot yet fully rule out a lensed double image.

Peer reviewed · Observations of one system · Masses are estimates

Astronomers have found the tightest quasar pair candidate known from cosmic dawn, the universe’s first billion years. Silvia Onorato of NSF NOIRLab and 34 co-authors report in The Astrophysical Journal Letters that the quasar J1602+4228 has a companion just 5.56 kiloparsecs away in projection, seen when the universe was about 900 million years old. Both black holes are already huge, which sharpens an old puzzle about how black holes grew so fast so early. The catch is that a gravitational lens making one quasar look like two is disfavoured, not excluded.

Evidence at a glance

Is this a big deal?

A solid detection with an interpretation still open. It is the most compact pair candidate found this early, and the clustering excess is striking. But it is one system, and the “earliest” part is a near tie: a debated pair called J1215−0148 sits at redshift 6.05, only about 6 million years later in cosmic time.

What scientists found

A quasar is a supermassive black hole swallowing gas so fast that the glowing gas outshines its whole galaxy. J1602+4228 was found in 2004. Webb showed a fainter quasar right next to it, at virtually the same redshift (6.0781 and 6.0785).

From the width and brightness of hydrogen lines, the team estimates the bright quasar’s black hole at about 1.5 billion solar masses and the faint one’s at about 400 million. Both are feeding near or slightly above the Eddington limit, the rate at which the push of radiation on infalling gas balances gravity (Eddington ratios of about 1.23 and 1.07, with roughly a factor-of-2 scatter).

The bright quasar alone radiates about 2.4 × 10⁴⁰ watts, about 60 trillion times the Sun’s output. “There is no definitive theoretical explanation for how a single one of these giant quasars exists so early in the age of our Universe, much less two,” Onorato said in the NOIRLab release.

How they found it

The Aether survey, led by Emanuele Paolo Farina of NSF NOIRLab/Gemini, uses JWST program 5645 to take a spectrum at every point around 200 quasars from 5.7 < z < 7, about 43% of those known in that range. Going through every data cube by eye, the team found exactly one companion quasar across the whole survey.

The separation is tiny on the sky. At 0.98 arcseconds, the pair spans about the angle of a 2.4 cm coin seen from 5 kilometres away. The comparison holds only for angle: the real gap is about a fifth of the Milky Way’s width, according to NOIRLab.

Gemini North’s GNIRS then took near-infrared spectra of both quasars with a single slit. The faint companion needed careful work: the team modelled and subtracted a nearby foreground galaxy from the data. Onorato said in the release that the sky over Maunakea was clear enough to collect the data in two nights. GMOS added optical spectra to test the lensing idea.

Why it matters to you

Nothing here touches daily life. It speaks to a question about origins: how the first giant galaxies and their black holes were built. If the two host galaxies merge, their black holes could one day form a binary of the kind gravitational-wave searches look for, though this paper does not test that step.

The growth puzzle in numbers

A black hole feeding at the Eddington limit with a typical 10% radiative efficiency grows by a factor of e (about 2.7) roughly every 50 million years. Reaching 1.5 billion Suns from a 100-Sun seed left by an early star takes about 16.5 of those steps, or about 830 million years of nonstop feeding.

The universe was only about 900 million years old at redshift 6.08, and the first stars that could leave such seeds appeared no earlier than about 100 million years after the Big Bang (around redshift 30). The timeline barely closes, and only with no pauses in feeding. A heavier starting seed of 10,000 or 100,000 Suns would cut the time to about 600 or 480 million years. This system doubles the problem: two such black holes in one small patch of sky.

What the evidence does not show

• It is not proof of a pair. The quasars differ in continuum slope, dust reddening and broad-line shape, but tiny stars in a lens galaxy can alter those (microlensing). The strongest evidence is the narrow oxygen line ([O III]): its outflow wings differ between the two, which a lens should not produce. A candidate foreground galaxy near B looks too extended to be a strong lens.
• The separation is projected. The 15 km/s velocity difference has an assumed 100 km/s uncertainty, so the pair could be farther apart along our line of sight.
• The masses are estimates from a single spectrum each, with about a factor-of-2 systematic uncertainty. Using a different hydrogen line gives 1.75 billion and 260 million Suns.
• The clustering excess comes from one detection, and theory at such small scales is, in the authors’ words, “extremely uncertain”.

How this fits what we already knew

Close quasar pairs are common in the nearer universe but scarce early on. The paper lists just three known beyond redshift 5: CFHTLS J0221−0342 (z = 5, 135 kpc apart), J2037−4537 (z = 5.66, 7.3 kpc) and J1215−0148 (z = 6.05, 12 kpc), whose pair status is still debated. Theory already says early giant black holes should sit in rare, massive dark matter clumps. The authors propose that this pair marks such a peak, where merging galaxies feed both black holes, or an as-yet unseen population of merger-triggered quasar pairs.

At later times, JWST has seen feeding black holes much closer together, such as LID-1166, about 4,900 light-years apart at about 1.3 billion years after the Big Bang. Aether cannot spot pairs closer than about 0.8 kpc, the limit of the NIRSpec IFU’s resolution.

What the name means

Nāpōwawāʻenakaulua was created by Larry Kimura, a professor at the University of Hawaiʻi’s Ka Haka ʻUla O Keʻelikōlani (Hawaiian Language College), through the A Hua He Inoa program at the ʻImiloa Astronomy Center. It joins Nā (plural), Pō (fathomless darkness, the black holes), Wawā (procreation or reincarnation), ʻEna (the brilliance of heat, their glowing gas) and Kaulua (a pair). NOIRLab renders it as “Two celestial bodies of fathomless powerful darkness in the brilliance of heat reincarnating energy into the Universe.” Kimura is a co-author of the paper.

Outside views

SciQuest has not interviewed an independent researcher for this story, and the coverage we found quotes no outside expert. The closest independent check in print is the paper’s own comparison with earlier pairs, which other teams discovered. We will add outside comment if we obtain it.

How other headlines framed it

Only release-based coverage exists so far, so the useful comparison is between the release and the paper:

• NSF NOIRLab headlined it as the “Oldest Compact Quasar Pair in the Universe” and said the universe was “a thirteenth of its age”. Using the paper’s own cosmology, 900 million years is closer to one-fifteenth of today’s age.
• Phys.org republished the release under a headline about a black hole growth puzzle.
• The paper is more careful: it calls the system the most compact quasar pair “candidate” in the Epoch of Reionization and nowhere claims the most distant or oldest pair.

What happens next

The team has a lens-modelling study and a dynamical analysis of the gas between the quasars in preparation, plus a survey-wide search for companion galaxies. Spectroscopy of the candidate foreground galaxy would test the lensing idea directly. A larger sample of pairs is needed before the clustering excess can be trusted.

In one sentence

Webb and Gemini North have found two giant black holes feeding about 18,100 light-years apart only 900 million years after the Big Bang, a pairing that deepens the mystery of fast early growth if a lens model confirms they are really two.

Read next

• Two feeding black holes found 4,900 light-years apart: a closer pair, seen later in cosmic history.
• What is the biggest black hole? Why most black-hole masses are estimates.
• How the James Webb telescope works: the infrared eye that found the companion.

Sources and disclosure

1. Onorato S, Farina EP, Decarli R, Protušová K, Pizzati E, et al. (35 authors). “Nāpōwawā‘enakaulua: A Close Quasar Pair at Cosmic Dawn in the Aether Survey.” The Astrophysical Journal Letters 1011, L59, published 10 November 2026. doi:10.3847/2041-8213/aeb11f. Open access, CC BY 4.0.
2. NSF NOIRLab release noirlab2627, “Astronomers Discover Nāpōwawāʻenakaulua, the Oldest Compact Quasar Pair in the Universe,” 10 November 2026: noirlab.edu (source of the Onorato quotes, the naming note and the Milky Way comparison).
3. Inayoshi K, Visbal E, Haiman Z. “The Assembly of the First Massive Black Holes.” Annual Review of Astronomy and Astrophysics 58 (2020). arXiv:1911.05791 (background on early black-hole seeds).
4. Republication read for framing: Phys.org, 10 November 2026.

Disclosure: This article was drafted with AI assistance and checked against the sources above, including the full paper. Calculations by SciQuest: 5.56 kpc × 3,262 light-years per kpc ≈ 18,100 light-years; 0.98 arcseconds = 4.75 × 10⁻⁶ radians, so a 2.4 cm coin subtends it at about 5.05 km; bolometric luminosity 2.37 × 10⁴⁷ erg/s = 2.37 × 10⁴⁰ W ≈ 6.2 × 10¹³ Suns (3.828 × 10²⁶ W each); cosmic age at z = 6.08 is 0.90 billion years versus 13.47 billion today (ratio about 1/15) for H₀ = 70 km/s/Mpc and Ω_m = 0.3, and 0.92 versus 13.79 billion with Planck 2018 values; z = 6.05 is about 6 million years later; Eddington e-folding time = 0.1/0.9 × 450 million years ≈ 50 million years, so growth from 100, 10,000 and 100,000 Suns to 1.5 billion takes about 827, 597 and 481 million years. The graphic is a SciQuest original built from the paper’s values and these calculations. Spotted an error? See our corrections policy.