Earliest known compact quasar pair poses a black hole growth puzzle

The James Webb Space Telescope and the Gemini North telescope have identified two supermassive black holes feeding side by side when the universe was less than a billion years old. According to Martin Cid Magazine, they form the oldest compact pair of quasars ever identified. The system is officially called J1602+4228AB and carries the Hawaiian name Nāpōwawāʻenakaulua, meaning “Two celestial bodies of fathomless powerful darkness in the brilliance of heat reincarnating energy into the Universe,” which was created by Larry Kimura through the A Hua He Inoa naming program. The study describing the system is led by Silvia Onorato of NSF NOIRLab and appears in The Astrophysical Journal Letters. Space reports that the light from the pair left about 900 million years after the Big Bang, corresponding to a redshift of about 6.08. The larger black hole in the system weighs about 1.5 billion times the mass of the Sun, while the smaller one weighs about 400 million solar masses. They are separated by roughly 18,100 light-years, which is about one fifth of the diameter of the Milky Way and shorter than the distance between our Sun and the center of the Milky Way. Tech Times notes that both black holes are feeding at or slightly above the Eddington limit, growing about as fast as physics normally allows. Silvia Onorato stated, “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.” The pair was discovered in the Aether survey, led by Emanuele Paolo Farina of NSF NOIRLab and the International Gemini Observatory. The survey uses the Near-Infrared Spectrograph on the James Webb Space Telescope to target 200 quasars from the first billion years. During a visual check, researchers noticed a faint companion near the known quasar J1602+4228. To confirm the companion as a separate object, the team used the Gemini Near-Infrared Spectrograph on the Gemini North telescope on Maunakea in Hawaiʻi, collecting data over two nights with a clean sky. Onorato noted that the data was gathered quickly because “the sky over Maunakea was so clean and sharp that we managed to collect the data in only two nights.” This system is only the third quasar pair found at cosmic dawn and is the tightest known. The previous most compact early pair, J2037-4537, has a separation of about 24,000 light-years, while another candidate, J1215-0148, is about 39,000 light-years wide. Researchers considered whether gravitational lensing could be creating two images of a single quasar, but spectra rule out this possibility because the two objects differ in light slope, dust dimming, and the shapes of gas outflows. However, archival Hubble images show a possible foreground galaxy near the fainter quasar, and a full lens model is still in preparation. The authors suggest that the pair marks an extreme peak in matter density in the early universe, where colliding galaxies drove gas toward their centers to fuel star formation and both black holes simultaneously.