Webb telescope spots oldest and most compact pair of quasar black holes

The James Webb Space Telescope has detected the oldest known pair of supermassive black hole-powered quasars, a finding that puzzles astronomers because the objects appear to have grown too quickly for current theories to explain.

The quasar pair, designated J1602+4228AB and nicknamed Nāpōwawāʻenakaulua, is seen as it existed 900 million years after the Big Bang. The two black holes have masses of 1.5 billion and 400 million times that of the sun, and are separated by only 18,100 light-years — about one-fifth the width of the Milky Way. This makes them the most compact quasar pair ever found from the Cosmic Dawn era, the period shortly after the first stars and galaxies formed.

“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,” said research team leader Silvia Onorato of NOIRLab in a statement. The discovery was made using data from Webb’s Aether survey, which has uncovered about 200 early-universe quasars. The Gemini North telescope on Maunakea in Hawai‘i helped confirm the pair by taking advantage of ideal weather and timing.

Current models suggest black holes need at least 1 billion years to feed and merge to reach such large masses, yet Webb has found supermassive black holes powering quasars as early as 400 million years after the Big Bang. Nāpōwawāʻenakaulua is the third quasar pair seen at Cosmic Dawn, adding further pressure on existing theories of black hole growth.

The findings were published on November 10 in The Astrophysical Journal Letters. Onorato described the system as a unique laboratory for studying how early massive galaxies and their central black holes assembled through direct interactions.